ExtendSim 10.0.4 was released on March 19, 2019.

The prior release, ExtendSim 9.2, was released on February 13, 2015.

If you are using ExtendSim 9 or earlier, we recommend you upgrade to ExtendSim 10.

To see the complete history of ExtendSim, go to the Evolution of ExtendSim.

Most companies find it cost effective to install a mix of ExtendSim license types depending on team member usage. Our suggested guidelines are:

Team members using ExtendSim for long periods of time or intensely during the day - so full-time users - will need Individual licenses.

If you have 3 or more part-time ExtendSim users, a Floating license might be your most cost-effective option.

If you have a computer in a secure environment that needs to be accessed by multiple team members, install a Node-Locked license.

All 3 license types are available for all Model Developer Editions of ExtendSim: CP, DE, and Pro.

It is always highly recommended to use the most current release of any software tool – as is the case with ExtendSim. Current releases take advantage of hardware and software advances and interact more appropriately with other new software packages. Plus, the current release of ExtendSim 10 can run models that were built in ExtendSim 9, 8, and 7.

However, there are reasons you might need to use a legacy ExtendSim product:

If ExtendSim 10 has not yet been approved for use by your company or organization.

Your collaboration team is still using ExtendSim 9 and you are working towards transitioning them to 10.

You are a student and your course materials use ExtendSim 9. (Many professors will not be updating their materials until 2019.)

ExtendSim 9 will only be available for purchase for one year following the release of ExtendSim 10 and is subject to annual Maintenance & Support fees. Please click on the icon of the legacy package you wish to purchase:

ExtendSim Suite 9 ExtendSim AT 9 ExtendSim CP 9 ExtendSim Student 9
ExtendSim Suite 9 ExtendSim AT 9 ExtendSim CP 9 ExtndSim Student 9

Note: As ExtendSim 9 is legacy software, it will no longer be updated or guaranteed to run on future operating systems.

Please contact Imagine That Inc. if you have questions about ExtendSim legacy products.

The ExtendSim License Agreement for an Individual license states:

"A single identified individual (the “Authorized User”) may use the Software. The Software may be used by the Authorized User only for the Company’s own internal business purposes or for your own personal use (if you are an individual), as applicable. Shared use, use by more than one individual, or use over a local-area network (LAN), a wide-area network (WAN), or the internet is prohibited under this License Option."

This means you are permitted one activation of your ExtendSim license for your own use. You may move your license from one of your computers to another at any time. But will have to deactivate ExtendSim on the first computer before it can be activated on a second as ExtendSim will not permit an additional activation.

Details on activating and deactivating ExtendSim licenses can be found at Installing & Activating an ExtendSim 10 Individual License.

Within the first 30 days of purchase, registered users are entitled to 100% trade-in credit for each Individual license converted to a station on a comparable or higher Floating license product.

If it has been more than 30 days since purchase, registered users with a current license are entitled to 75% trade-in credit for each Individual license converted to a station on a comparable or higher Floating license product.

If you are using a version prior to the current version, the trade-in credit will be reduced by the price of the upgrade.

Software refund policy

Downloaded software cannot be returned. An Activation Key is provided, but no physical product is shipped so there is nothing to be returned. Imagine That Inc. offers a complimentary 30-day trial of ExtendSim for evaluation. It is assumed that the buyer has reviewed his/her product of choice and is completely satisfied with its quality before effecting actual purchase of said product. If you have not taken advantage of the Trial version, please do so before purchasing any of our products. With knowledge of the above, no refund/return request should be solicited by the buyer/user on such basis.

Training refund policy

See Training Cancellation Policy.

Does ExtendSim have a VPAT showing its compliance with Section 508 of the Rehabilitation Act (accessibility of data and information to people with disabilities)?

Yes. Please see ExtendSim Section 508 VPAT (Voluntary Product Accessibility Template).

We could set up dozens of matrixes and comparative documents that boast about how awesome ExtendSim is and slant the results in our favor since we would be 'authoring the study'. But that's not right as your needs are vastly different that most others. We are happy to give you guidelines about how ExtendSim is designed and how it would handle the various challenges you could put it up against. But in the end, you are the best determinant of which tool would best suit your particular needs.

So, ask us questions - any question - and we're happy to tell you how ExtendSim works. If you want to know how it is as compared to other packages, we could provide you with our personal opinions, but it's probably best to ask those that have used multiple packages in their modeling careers. Check out what other simulationists are saying in the ExtendSim Exchange.

Yes and no... and yes it will! Confusing? Let us explain. 

The application gurus at Imagine That Inc. are hard at work on the Mac version of ExtendSim 10 right now. It should be just like the Windows version, but able to run natively on a Mac. And you will be able to exchange your ExtendSim models back and forth with colleagues between the 2 operating systems. We don't have a specific date when ExtendSim for Mac will be ready, but we will keep you updated.

What are my options today?

Run the Windows version of ExtendSim on your Mac, but in the Windows operating system. To do this, you need to obtain the Windows operating system and an emulator. You can use Boot Camp Assistant (installed with the Mac operating system in the Utilities folder under Applications). Or install the emulation software Parallels (www.parallels.com). During installation, Parallels will request the Windows operating system installer to complete the process. Once the installation is complete, you can install the Windows version of ExtendSim.

Run the Windows version of ExtendSim on a Windows computer.

Do earlier versions of ExtendSim for Macintosh run on current Mac systems?

Legacy versions of ExtendSim (9 and earlier) did have version that would run on Macs, but they will NOT run on current Macintosh operating systems OS X 10.7+. Legacy versions of ExtendSim for Macintosh can run on Mac OS X 10.6.8 and earlier. If you are using a Macintosh with OS X 10.7 or newer, use the Windows version of ExtendSim running in Parallels or BootCamp.

Enjoy it for 30 days from the date you first launch ExtendSim. Once you reach the end of that month – if you haven’t already purchased the product – that free Trial period will end. All the model files and blocks you created during that Trial period will still be yours, but ExtendSim will not longer launch on your system. However, you will still have access to the Activation dialog where you can purchase and/or activate ExtendSim.

Each time you launch ExtendSim in Trial mode, the activation dialog appears. The number of days remaining in your Trial period is in the upper right corner of the dialog.

When you first launch the Trial version of ExtendSim, you have 30 days to try it out. Once you reach the end of that month – if you haven’t already purchased the product – that free Trial period will end. All the model files and blocks you created during the Trial period will still be yours, but ExtendSim will no longer launch on your system.

If you try to download and install another Trial version to get another 30 days, it won't work. Your system will only allow one free trial period.

Absolutely! All the model files and blocks you create during your 30-day Trial period will seamlessly open in any Model Developer Edition...Individual, Node-Locked, or Floating ExtendSim license.

In fact, once you activate your Trial version, you'll notice the "Trial version" watermark on the model worksheet will disappear.


Please note, if you build a model in a Trial version and share it with someone who has a Student version of ExtendSim, they will not be able to open your model. Student versions can only open models built in an activated MDE license or from another Student version.


Absolutely! As long as the model you want to run was built in a Model Developer Edition of ExtendSim, you will be able to run it in Trial mode. Just know that their model will open with a "Trial version" watermark behind the model on its worksheet in your Trial version.

Please make sure you are using the same ExtendSim package the model developer used to create the model. For example, if your colleague built a model using ExtendSim Pro, you would need to be using the Trial version of ExtendSim Pro, not DE or CP as they may not have the proper components to run the model.

No. It is identical to a Model Developer Edition of ExtendSim with the exception of two things:

ExtendSim will only launch for 30 days in Trial mode. After that, it must be activate to a fully licensed version.

When you open or build models in Trial mode, you will see a "Trial version" watermark behind each model. This watermark gets saved with the model. To get rid of the watermark, activate your ExtendSim license and re-save the model.

When you purchase and activate ExtendSim CP, DE, or Pro, the activated license will open the model you built while in Trial mode and remove the Trial Version watermark.

No. The Student version of ExtendSim can open models built in or shipped with ExtendSim Student or in an activated Model Developer Edition of the software.

Activation is usually accomplished automatically and within seconds via the internet.

Sometimes that process does not work as intended. The main problems activating a license are:

Your device is not allowed access to the internet or the internet is down. In this case, you need to manually activate ExtendSim. Please see Installing & Activating an ExtendSim 10 Individual License.

Bad HTTP transaction. Error: License Generator not found at this URL. Please try again.Your device has an internet connection, but you get an error message indicating that activation cannot be completed. This is usually caused by a virus protection application or a firewall blocking activation. You can either manually activate ExtendSim or temporarily turn off the virus protection to allow ExtendSim to communicate through your firewall.

To temporarily turn off virus protection on your computer to allow ExtendSim through the firewall, go to Settings > Update & Security > Windows Security (on left hand side). Under Protection Areas, select "Firewall & Network Protection" and "Allow an app through the firewall". Then click the "Change Settings" and "Allow another app" buttons. Browse to ExtendSim 10 and click Open. In the dialog that appears, click Add. Then try activating again.

Manually activating ExtendSim bypasses your device's lack of internet access or its blocking of communication (via firewalls or the like). For details on manually activating ExtendSim, please see Installing & Activating an ExtendSim 10 Individual License.

Moving ExtendSim from one device to another works the same as for most applications.

First, make copies of your ExtendSim models, any custom blocks, etc.

Deactivate ExtendSim on the previous device using the Help > Deactivate ExtendSim command.

Install ExtendSim on the new device by downloading the appropriate Trial version.

Paste your model files, etc. from the previous device to the new installation of ExtendSim.

Launch ExtendSim on the new device and activate it using the same Activation Key you used for the first installation. (If you can't deactivate ExtendSim on the previous device, you will get an error message stating your Activation Key is already in use on another device. In this case, contact Imagine That Inc.)

For complete installation instructions, see Installing & Activating ExtendSim Individual Licenses.

Do you own a current Maintenance and Support Plan (MSP) for your ExtendSim 9 license?

Terrific! Your upgrade is free! Click on the icon below of the package you wish to upgrade to.


Never owned an MSP for ExtendSim 9?

You will have to purchase your upgrade. Click on the icon for the ExtendSim package you wish to upgrade to. You'll be able to pay for your upgrade and download a Trial version of 10 from here.


                     ExtendSim CP                    ExtendSim DE                     ExtendSim Pro           

Not sure which package you want to upgrade to? Check the ExtendSim Product Advisor.        

Depends on the type of models you're building. If you're building discrete event models, upgrade to ExtendSim DE. If you are using the blocks from the Rate library in your models or want to use the new Reliability components, upgrade to ExtendSim Pro.

For more details on which package may work best for you, use the ExtendSim Product Advisor.

ExtendSim 10 is upwardly compatible and will read in models built in legacy ExtendSim versions 9, 8, and 7.

If you created a custom library in a legacy version, before opening the model using the custom libraries, open the custom library. Go to Library > Library Tools > Compile Libraries... Select your custom library and click Compile Selected Libraries. This will recompile the library creating an ExtendSim 10 library with a .lbr extension. Then, open the model in ES10.

Note: ExtendSim 10 is not backwardly compatible. Models and blocks you build in ExtendSim 10 cannot be read by earlier versions, such as ExtendSim 9 or ExtendSim 8.

You cannot copy objects in models (graphics, text, hierarchical blocks, databases, etc.) from release 9 or earlier directly into ExtendSim 10. Instead you must open the model file in ES 10. Then, ExtendSim will convert it to an ExtendSim 10 file.

Choose About ExtendSim under the Help menu to open the ExtendSim start up screen. The bar at the top shows you which ExtendSim release you are using. If it does not say ExtendSim 10.0.4, you should download the most current release.

Use the Trial version of ExtendSim as your updater. Download the Trial version of the package you purchased and install over your current installation of ExtendSim 10.0.x. When you restart ExtendSim, you will be running 10.0.4.

goExtendSim CP 10.0.4

goExtendSim DE 10.0.4

goExtendSim Pro 10.0.4


This free update for Individual licenses of ExtendSim 10 not only optimizes the stability and quality of ExtendSim, but adds a couple of new features.

goQuality and Stability Enhancements in ExtendSim 10.0.4

An annual Maintenance & Support Plan (MSP) covers support, upgrades, updates, replacement and updated Activation Keys, and more. For details, please see Maintenance & Support Plan.

An MSP is required for all products except Trial, Analysis RunTime, and Player RunTime. The first year of Maintenance & Support is included in the purchase price of ExtendSim.

The Maintenance & Support Plan for your ExtendSim license begins the day you activate your software.

The renewal date is then visible on the start up screen each time you launch ExtendSim or accessible by going to the Help menu and selecting About ExtendSim.

Absolutely. Contact Imagine That Inc. and let us know which date works best for your team to renew your ExtendSim licenses. We can synchronize the renewal dates of your licenses to reflect a common MSP start and end date, regardless of when each product was first activated. Prorated charges will apply. We'd be happy to work up a quote for you.

The annual Maintenance & Support Plan (MSP) is renewable one year from date of purchase (or on your pre-established renewal date) and each year thereafter. How to renew depends on the type of license you own and how you want to pay:


Individual & Analysis RunTime licenses

Credit card renewal -- Click on the icon below of the ExtendSim package you own to be taken to the ExtendSim Store.

          promaintenance          demaintenance          cpmaintenance  

Purchase order renewal -- Use the MSP Annual Renewal Fee chart to determine the cost for your renewal. Submit your PO to This email address is being protected from spambots. You need JavaScript enabled to view it..


Floating, Node-Locked, & ASP licenses

Contact Imagine That Inc. for renewal fees and payment options.

No. You will keep the same activation key for your ExtendSim 10 license. Renewal is managed and updated through the Reprise License Manager (RLM). After renewing your MSP, we update RLM with your new renewal date. The next time you launch ExtendSim, the software reaches out to the RLM server and acquires the new renewal date.

If your computer is not connected to the internet, let us know when you rewew your MSP. We can send you a license file that you can use to manually update the renewal date of your software.

Yes. Both the License Manager and Client devices could be virtual machines.

Log into the License Manager (ExtendSimLicServer) on the Server:

Open a browser on the Server and enter localhost:5054 in the browser’s address line.

Or, open a browser on some other device that is on the same network as the Server and enter servername:5054 in the browser’s address line.

Not directly. Before you try to move the License Manager, contact us at This email address is being protected from spambots. You need JavaScript enabled to view it. or 1.408.365.0305. We will revoke the current license so you can activate on the new Server. Then uninstall the License Manager from the original server as instructed in Installing & Activating ExtendSim Floating Licenses.

See the instructions "Uninstalling the License Manager from the Server" on page 6 of Installing & Activating ExtendSim Floating Licenses.

Only for up to 90 days after you install ExtendSim 10. Otherwise, you would be violating the ExtendSim License Agreement by allowing double the number of concurrent users. By the end of the 90 days, you must uninstall the ExtendSim 9 Network License as discussed on page 6 of Installing & Activating ExtendSim Floating Licenses.

For release 9, run the “Remove ExtendSim Server.exe” file in the Server’s ExtendSimServer folder. You should get two messages:

License Successfully Removed

Service Successfully Removed.

Then use Windows Settings to uninstall the ExtendSim Server files.

Yes. However, how you make the change depends on your situation:

If you received the ExtendSim.lic file while doing a manual activation but haven't resumed the activation process, change the port number in the file before proceeding. Then complete the activation procedure. Be sure to give the updated ExtendSim.lic to each Client.

If you have already activated the License Manager either automatically or manually, you don't need to get a new license file from us. Instead, edit your existing ExtendSim.lic file using the steps outlined in "License Manager - Manual Activation" on page 3 of Installing & Activating ExtendSim Floating Licenses. Using a browser, open the RLSA window as indicated in the instructions. At step 6 copy the contents of your existing ExtendSim.lic file (located at C:ExtendSimFloatingLicenseServer) into the field and edit the port number in that field. Then follow the remaining steps to edit and update the file and restart the License Manager. Be sure to give the updated ExtendSim.lic to each Client.

Installing the ExtendSim.lic file on the Client device broadcasts to automatically find the Server. If it can’t find the Server, it asks you to enter Server info (URL or computer name, etc.). It saves that location info in a host.lic file on the customer’s device so it doesn’t ask again.

Yes. Go to Documents/ExtendSim10 and open the Host.lic file. It has the name of the Server.

The license file (ExtendSim.lic) on the Server needs to be updated whenever there is a change to the license. To update the license file, repeat the steps for License Manager Activation on page 2 of Installing & Activating ExtendSim Floating Licenses. After the Server’s license has been updated, the Client devices will automatically get the updated MSP information. There is no need to replace the ExtendSim.lic files on Client devices.

The license file (ExtendSim.lic) on the Server needs to be updated whenever there is a change to the license. To update the license file, repeat the steps for License Manager Activation on page 2 of Installing & Activating ExtendSim Floating Licenses. After the Server’s license has been updated, the Client devices will automatically get the updated count information. There is no need to replace the ExtendSim.lic files on Client devices.

Public Training Course Refund Policy

In order to maximize the effectiveness of our training classes, Imagine That Inc. limits the number of attendees per class. Registrants who have been confirmed for a specific training class may reschedule or cancel their class:

Up to 14 days before the course starts

Full refund

One to 13 days before course starts

$500 cancellation fee

No show or no advance cancellation

No refund

Imagine That Inc. reserves the right to cancel or reschedule any training class upon a fourteen (14) day notice to all confirmed registrants. Registrants may then reschedule into an upcoming training class or cancel the registration without penalty. The client understands and agrees that Imagine That Inc. shall not, in any way, be held responsible for any cost, including airfare, transportation cost, hotel expenses or other cost that the client may suffer in the event that Imagine That Inc. cancels or reschedules a class.


On-Site Training Refund Policy

When an on-site training class has been booked, the dates reserved have been set aside exclusively for you so that time period is unavailable to others who might want training. Travel and other arrangements for the course trainer are also made at the time the training is booked. Thus, our Refund Policy for on-site training different than for the Public Training:

Notify Imagine That Inc. of cancellation at least 21 days before the scheduled start of the course. This ONLY applies if the training was to be held within the contiguous United States. (For training in Alaska, Hawaii, and all countries outside of the USA, the full refund only applies if you cancel at least 30 days before the scheduled start of the course.)

Full refund (or no charge, as applicable)

Notify Imagine That Inc. of cancellation between 20 and 2 days before the scheduled start of the course. This ONLY applies if the training was to be held within the contiguous United States. (For training in Alaska, Hawaii, and all countries outside of the USA, the partial refund only applies if you cancel at least 5 days before the scheduled start of the course.) The partial refund (or partial charge, as applicable) consists of:

bulletgoldNo refund on instructor expenses. We will do our best to recover instructor expenses from vendors (airlines, hotel, etc) and will refund or credit you for any expenses we recover. But there is no guarantee that any of the instructor's expenses will be recoverable.

bulletgoldA $500 cancellation fee if the course was to be held within the contiguous United States; $1,000 cancellation fee otherwise.

Partial refund (or you will incur a partial charge, as applicable)

Unless you provide at least a 2 day advance notice of cancellation AND the training is within the contiguous United States, there is no refund on quoted charges for the training. (For training in Alaska, Hawaii, and all countries outside of the USA, there is no refund - or you will be charged, as applicable - unless you notify us of cancellation at least 5 days in advance of the training.)

ExtendSim training courses are available in one of our regional locations, through a certified ExtendSim Trainer, or even on-site at your facility. We have the flexibility to train virtually anywhere.

Multiple times throughout the year, beginning through advanced public training sessions are held in various locations around the world.

If you anticipate sending 3 or more employees to a public training course, you may want to consider on-site training. Courses can be scheduled at your convenience and in your facilities (anywhere in the world) as a privately held on-site training. We will send one of our authorized expert instructors to your site (with student laptops) for an intensive, hands-on, training. Plus, with on-site courses, there is the option to tailor the training to your environment and situation-specific needs.

See the complete course list to learn more details.

In other simulation tools, the items (also referred to as entities or transactions) are put on the event calendar (scheduled for future consideration when a time delay is encountered). In ExtendSim, the blocks have an entry on the event calendar. Some blocks contain their own event calendars with an entry for each item in the block.

Scheduling the blocks rather than the items has a number of advantages:

Because there are typically fewer event scheduling blocks in the model than there are items to be scheduled and the number of event scheduling blocks in a model does not change, the ExtendSim event calendar is relatively small. This eliminates the need for time consuming insertion and deletion of events on the calendar. This is particularly important in large model where searching the event calendar for the next event can be a large portion of the execution time.

It is very easy to change the event time. Because the block’s event time is stored in a fixed location, the future event time for the block can be changed with a simple assignment.

Items are not necessary for an event. A block can schedule an event without needing to create (and then dispose of) an item.

Any block in the model can schedule an event. This makes it particularly easy to build modeling components which simulate system features such as preemption and reneging. These types of features normally require internal or dummy items in other simulation tools.

ExtendSim uses both a push and pull mechanism to propel items through a model. Residence blocks (residence blocks are any block that can hold an item for a non-zero amount of time, such as queues, activities, resource blocks, and some decision blocks) attempt to pull items in until it is full or until there are no more items to pull in. Then the residence blocks will try to push items out until there are no items left or the downstream path is blocked. In some cases, the residence block will hold the item for a specific time delay before attempting to push the item out.

In ExtendSim 10, ARM records utilization and quantity utilization because it is now possible for a record in the [Resources] database table to represent a quantity of resources other than 1. In v9.2 and earlier versions of ExtendSim, each record in the [Resources] table represented exactly one resource. In the new version of ARM, a record in the [Resources] table now has an explicitly defined quantity field. The quantity can be any non-zero real or integer number. When any portion of the quantity of a resource record is BUSY, ARM tracks the resource record as being utilized. This utilization is recorded in the Utilization field. The Quantity Utilization is a measure of how much of the available quantity for the resource record has been utilized during the simulation run.‬‬ ‪

For example, a resource record has a quantity of 10. During the entire simulation run, a quantity of only 1 is continuously utilized. The Utilization for this resource record would be reported as 100%, but the quantity utilization would be reported as 10%.‬‬

Use a Write block (Value library) as an interface between the Database and the Optimizer (Value library). Follow these steps:

1. In a Write block, select the Database and table with the variables for the Optimizer.

2. Drag the clone of the preview table from the Write block to the Optimizer once per variable in the Optimizer.

3. Set the row and column in the Optimizer for the table. Remember that these are 0 based references (the first row and column are numbered 0).

When the Optimizer changes the variables, they will automatically be changed in the Database.

Showing simultaneous movement requires the use of a Transport and/or Convey Item block from the Item library (included in ExtendSim DE and ExtendSim Pro). To animate the simultaneous movement of items through a model, follow these steps:

1. Place a Transport or Convey Item block at the point in the model where you want a transit time. A transit time is required to show simultaneous movement, otherwise the movement would have no duration.

2. Open the block's dialog. On the Transport Animation tab of the Transport and/or Convey Item block, check the "2D animation shows simultaneous movement" option. Tip: Use the Find and Replace block from the Utilities library to change all of the blocks at once.

3. Select "in a straight line" or "along connections" for the movement.

4. Turn off "Add Connection Line Animation" from the Run menu.

Connect a Switch block from the Utilities library to the "Q" (Item Quantity) input connector on the Create block (Item library). If the Switch is On, a quantity of 1 is sent to the Create block and an item is created. When the Switch is Off, a quantity of 0 is sent to the Create block and no item is created.

The item will wait in the last upstream residence block until the Activity block (Item library) can receive it. Residence blocks are any block that can hold an item for a non-zero amount of time. Examples include queues, activities, resource blocks, and some decision blocks. If the last residence block is a generator type block, the item will be held until a new item is created or the activity pulls the item. This is the only time that an item will be destroyed if there is downstream capacity.

In a discrete event model, you can control the order that time ties (two or more events occurring at the same time) are processed. ExtendSim will put the blocks on the event calendar in simulation order. Blocks with a lower simulation order will receive their event message first. You can change the simulation order with the following steps:

Go to Run > Simulation Setup > Continuous tab. Under Simulation Order, choose Custom (Advanced only)

Under the Model menu, turn on Show Simulation Order.

Select an event scheduling block. Choose Set Simulation Order from the Model menu. Set your Custom Simulation Order.

Note, the simulation order will only make a difference if two or more events occur at exactly the same time. If the events are not exactly at the same time, events will occur in chronological order.

1. Are there any caveats to how I can use the RunSimulation, PauseSim, and ResumeSimulation functions?

These functions are not recommended for use via OLE automation or DDE Execute messages at all. These functions were developed before the External Scripting functionality was fully developed, and they do not work as well in this context as the ExecuteMenuCommand function. This function acts exactly as if you have selected the specified command from the menu bar and will perform better with the external control methods. The ExecuteMenuCommand function takes one argument, the command number. These numbers are defined in the Technical Reference.

2. Should I use a different modeling technique if I am running a simulation that basically finishes instantly versus running a simulation that will run for longer and want to control interactively?

There is a difference in how you should set up your code in these two cases.

If the simulation is going to complete instantly and/or you are not interested in sending other commands to ExtendSim while the simulation is running, you can just send the executeMenuCommand(6000) to ExtendSim without a worry.

If, however, you are interested in running a longer simulation, and you want to be able to pause and resume it or get data while the simulation is running, you should use the IPCServerAsync(TRUE); function. This function specifies to ExtendSim that the following Execute control action should execute asynchronously, not synchronously. A synchronously executed instruction will execute immediately and the application that sent the command will wait for the instruction to complete before it continues its execution. An async command, on the other hand, will return immediately allowing the application to continue on with other things while the simulation runs. The sequence of instructions you should execute in this case would be as follows:

a. IPCServerAsync(TRUE);

b. ExecuteMenuCommand(6000);

c. IPCServerAsync(FALSE);

These should be sent as three different execute messages. It is important to send the final IPCServerAsync(FALSE) and not to send any other Async messages while the simulation is running, as ExtendSim doesn't allow multiple asynchronous messages to be processed simultaneously.

If you add new dialog items or static variables to your custom block, they will need to be initialized. The easiest way to do this is in the openModel message handler. This is called whenever a model is loaded. If you delete or change the dimensions of dialog items or static variables, the data in the existing blocks may not match up correctly with the data in the existing blocks. To avoid this, delete the existing blocks and re-add them to the model. You can also use the "hide" feature to hide the dialog item. You should do this if your blocks are being used in models where it would be inconvenient to replace each instance of the block.

...I would like to use the Interchange block (from the Rate library in ExtendSim Pro) to represent the berth. Vessels would come to either load or unload. Can I use just one Interchange block to both load and unload?

Yes. In fact, there are three different ways to model a berth that is used both for loading and unloading:

Solution 1 -  One Interchange block simulates the ships at berth and the berth itself.

Solution 2 - One Interchange block simulates the ship loading or unloading and Tanks and Valve simulate the loading and unloading of product to and from the berth.

Solution 3 - One Interchange block is used for unloading and one Interchange block for loading.

downloadAll three solutions are illustrated within this freely downloadable model that illustrates how to load and unload at the same physical location.

Note: This model was built in ExtendSim 9 so can be viewed in either ExtendSim 9 or 10.

If you use screen shots that contain ExtendSim blocks on your web site or in any printed matter, please post or footnote this statement:

ExtendSim blocks copyright © 1987-2018 Imagine That Inc. All rights reserved.

Before quoting any documentation from the ExtendSim documentation, blocks, Help, or the Imagine That Inc. web site, you must get prior written permission from Imagine That Inc. Once permission is granted, please include this statement:

Portions copyright © 1987-2018 Imagine That Inc. All rights reserved.

If you build custom blocks based on ExtendSim blocks, hence using copyrighted information from certain libraries in the ExtendSim products, your right to sell, give, or otherwise distribute the blocks you have developed is restricted. In that case, your blocks may only be sold, given away, or distributed to a recipient who has the same ExtendSim package that you used to develop your blocks. For more information, see the copyright notices at the front of the ExtendSim User Reference.

When sharing your ExtendSim models and/or custom libraries with fellow employees, customers, or others (“end users”), the end user will either:

Already have a full Model Developer Edition (MDE) of ExtendSim.

Not want to purchase a full version of ExtendSim.

If the end user is using an MDE of ExtendSim:

In most cases, you can just provide your models and custom libraries to the end user. However, if your model uses blocks from the Discrete Event, Discrete Rate, or Reliability libraries, or your custom libraries have been derived from ExtendSim libraries in the ExtendSim DE, or ExtendSim Pro products; the end user must also have the comparable ExtendSim product. If the model you are sharing contains custom-built blocks, please see Delivering Custom Files to an End User below.

If the end user does not own ExtendSim:

The Analysis RunTime license is the perfect solution for end users who do not have an MDE version of ExtendSim. The Analysis RunTime license is a cost-effective way to access advanced ExtendSim functionality, without having to purchase a development version of ExtendSim.

As the developer, it is your responsibility to supply the end user with the necessary files and sufficient information to install those files. Use this as a guide to ensure the end user has all the necessary components to view and run your model:

An ExtendSim license. See Running shared models above.

Your ExtendSim models. If you wish to prevent blocks being added, deleted, or moved in your models, give the Model > Protect Model command and use a password.

Any custom libraries the model/s require.

If you do not want the end user to be able to build models with your custom library, convert the library to RunTime format. For those using the Analysis RunTime or Player RunTime license, this is mandatory as your custom library MUST be in RunTime format so the end user can run models using that library.

If you want the end user to be able to use your libraries to build models and they're using a full Model Developer Edition of the software, you must also send them copies of your libraries that are NOT RunTime formatted.

To prevent access to the source code, you can use the Library > Library Tools > Protect Library command; this removes the source code from all the blocks in the library.

Any extensions required by your files.

Installation and model usage instructions.

RunTime formatting is helpful for library developers because it limits the use of libraries and protects block source code:

A library in RunTime format can be used by an Analysis RunTime, Player RunTime, Student, or Model Developer Edition to run models, but not to build models.

Libraries that are in RunTime format are protected in that block source code is stripped from each block making your custom source code inaccessible to the end user.

Model Developer Editions of ExtendSim cannot fully use libraries that have been converted to RunTime format. (MDE users can open a model that uses RunTime formatted libraries, but the end user will only be able to run the model, not make changes.)

To convert your custom libraries to RunTime format (Note: RunTime versions of ExtendSim ship with RunTime versions of all ExtendSim libraries so you will only need to convert any custom libraries you might build.):

In ExtendSim, choose Library > Library Tools > Convert Library to RunTime Format.

Select the library for conversion. ExtendSim will make a copy of the library, convert it to RunTime format, and save it in the same location as the original library.

Libraries converted to RunTime format keep the same name as the original, but add the extension “.lbrrt”.

Since the library name is the same, models opened by the Analysis RunTime, Player RunTime, Student, and Model Developer Edition of ExtendSim will recognize the reformatted libraries as if they were the originals. (Note, however, that the full version of ExtendSim will not allow the end user to build models with RunTime formatted libraries.)

You might see this happening if you're running ExtendSim on a Windows OS version prior to 8.1.

To correct this:

Right-click on your desktop

Go to Display Settings

Scroll down to Scale and Layout and Change the size of text, apps, and other items to 100%.

If you have multiple ExtendSim licenses on your computer (for example a Model Developer Edition and an Analysis RunTime version), it is generally better to open the ExtendSim license you want to use first, then open the model. If you double-click on a model file, it will open the last ExtendSim license installed.

If the proper version of Excel is not installed on your computer, you will see the error "OLE CreateObject Not Successful" when you try to access an Excel spreadsheet from within ExtendSim. Possible causes of receiving this error are:

Excel is not installed on your computer.

Excel is installed on your computer, but the installation is damaged. In this case you will need to reinstall Excel.

A “click-to-run” version of Excel is installed on your computer. This version does not support communication between outside applications such as ExtendSim and Excel. You will need to uninstall your click-to-run version of Excel and install a full version of Excel. Instructions for this can be found at support.microsoft.com/kb/982431

The error "Run-time error 429: ActiveX component can't create object" might occur if you try to launch ExtendSim (as a server) from an outside application (as the client) in an ActiveX/COM client/server process. In order to interface with Excel or other outside applications using ActiveX/COM, ExtendSim must be registered as an OLE/COM server. Many companies restrict an employee's application permissions to the most basic. To register ExtendSim as an OLE/COM server, you must launch ExtendSim one time with Administrator permissions. To do this, right click on the ExtendSim.exe file and select "Run as: Administrator" (you'll probably need a password from your IT department).

Because ExtendSim has its own compiler, it executes compiled code. Windows can interpret this code as data, rather than code, that is executing. The default setting for Data Execution Prevention (DEP) is "Turn on DEP for essential Windows Programs only." Some Windows installations don't use the default; this causes a problem for ExtendSim. In certain cases, ExtendSim will crash upon launch and return the error message "Unknown msg Unknown block". To correct this problem, follow these instructions.

From the Windows Control Panel, find "System & Security or Maintenance".

Click "System", then go into "Advanced System Settings".

Under "Performance", click the "Settings" button.

Select the "Data Execution Prevention" tab.

Select "Turn on DEP for essential Windows Programs and service only" ...OR... Select ""Turn on DEP for all programs and services except those I select". Then, Add "ExtendSim.exe" to the list.

If the computer you have installed ExtendSim on does not contain the Universal C Runtime in Windows, the following error message (or something similar) may appear while trying to launch ExtendSim (or other newer applications):

The program cannot start because api-ms-win-crt-runtime-l1-1-0.dll is missing from the computer.
Try reinstalling the program to fix this problem.

You will need to install the Universal C Runtime (CRT) update on your Windows operating system to enable newer applications (like ExtendSim) to run on a Windows OS earlier than 10. The Microsoft web site offers instructions for updating the Universal C Runtime component.


The ExtendSim Installer is probably being blocked from installing "ExtendSim_DB_Connector.dll" if you see the message "codebase failed to register". Extension error messageOr after launching ExtendSim and the Getting Started model opens, but reports that "_RightClickConnect database" is missing, Extensions have been blocked.

The problem is that your virus protection program has blocked the installation of files in the ExtendSim10/Extensions folder. To be sure Extensions are properly installed, temporarily turn off the virus protection program and re-install ExtendSim 10; you can reinstall over the existing installation. When finished installing, turn the virus protection program back on.

If you see the error message "codebase failed to register", the Installer is being blocked from installing "ExtendSim_DB_Connector.dll". Or when you launch ExtendSim and it opens the Getting Started model, but reports that "_RightClickConnect database" is missing, extensions are being blocked during installation of ExtendSim 10.

The problem is that your virus protection program is blocking the installation of files in the ExtendSim10/Extensions folder. Temporarily turn off the virus protection program and reinstall ExtendSim 10; you can reinstall over the existing installation. When finished installing, turn the virus protection program back on.

There are two levels of ExtendSim 10 definitions:

Compile Time -- If you are compiling a block in ExtendSim 10, EXTENDSIM_10 is defined by the compiler so can be used in block code with a value of 1. Your block code might be similar to:

#ifdef EXTENDSIM_10
    #include "v10 include file.h"
    and some v10 compatible code;    // note that this can use V10 functions that are not defined in V9 as v9 will ignore this
    #include "v9 include file.h"
    and some v9 compatible code;

Run Time -- Your block could call GetExtendVersion(0), which returns a double of 1000.0 or greater for version 10.xx. Your block code might be similar to:

if (GetExtendVersion(0) >= 1000.0)
    do something that v10 needs (must use v9 compatible functions if you need to run this block in v9);
    do something that v9 needs;

All ExtendSim versions are upwardly compatible. So ExtendSim 10 will read in models built in ExtendSim 9, 8, and 7. ExtendSim 9 will read in models built in ExtendSim 8, 7, and Extend 6. And so on.

However, ExtendSim is not backwardly compatible. Models and blocks you build in ExtendSim 10 cannot be read by earlier versions, such as ExtendSim 9 or ExtendSim 8. Models and blocks you build in ExtendSim 9 cannot be read by earlier versions, such as ExtendSim 8 or ExtendSim 7.

Your computer has probably been updated to Windows 10. In October 2017 Microsoft began rolling out Windows 10 Fall Creators update, release 1709. As with any update, there were some problems and some unintended consequences. One change was how the Windows memory manager worked, which caused a problem for older installations of ExtendSim such that it could hang up or crash on launch.

If you are using ExtendSim 7.0 to 9.2 released prior to November 16, 2017, get your fix file here.

If you are trying to enter numbers into editable text boxes in a block dialog and nothing appears, the problem could be that your system has been set to use right-to-left text for programs that do not use Unicode. This setting will work for programs that are built to expect to use right-to-left text, but not for programs that are not set to expect this.

You may need to change your system locale. The system locale determines the default character set (letters, symbols, and numbers) and font that you use to enter information and that are used to display information in programs that do not use Unicode. Selecting a different language for the system locale will not affect the language in menus and dialog boxes for Windows or other programs that do use Unicode. Try changing the default locale to English (United States) and check to see if this helps.

To change the system locale, follow the instructions at: answers.microsoft.com/en-us/windows/forum/windows8_1-desktop/how-to-change-the-system-locale-to-run-non-unicode/7a7c2bd2-b67b-4f89-ad76-04c2346e01c0.

If you receive an error message on your client installation when trying to check a license out of your ExtendSim 9 network license it is probably the result of not having sufficient permissions on your client machine to checkout the license. The checkout process requires some administrative rights on the client machine and many companies are restricting these rights from users.

Try using the right-click command "Run as administrator". If this doesn't work, then you may not have been granted sufficient permissions by your company on the machine to check out a license.