Page 324 - ExtendSim User Guide
P. 324

Statistics and Model Metrics
Using the History block to get item information
• Connect it in series by dragging a History block from the Item library and connecting it between other blocks so that items pass through it.
• Connectitinparallelbyright-clickinganitemoutputconnectorandselectingAddHistory block. This automatically connects a History block to the original block’s item output con- nector. If a History block is added in this manner, only its input connector is used. (Caution: Be sure there is an Item library block connected to the original block’s item output connec- tor, otherwise its item will have no place to go.)
Each item that passes through the block (if it is connected in series) or is viewed by the block (if it is connected in parallel) is allocated a row in the History block’s table. The table’s first column displays the item’s arrival time. Popup menus at the top of the other columns are for selecting additional information to display, such as the value of an attribute, an item’s property, and so forth. You can choose to save item history with the model, show string attributes, and display Calendar dates.
☞ History blocks can use a lot of memory. To temporarily disable the recording of messages during a run, check the Disable Recording box in the Options tab. For blocks that have been added to the model by right-clicking, right-click to disable message recording or to delete the blocks.
History model
The History model shows two History blocks: one has been physically placed in series between a Queue and an Activity and one has been auto-created and placed in parallel to the Queue block.
Both blocks report the same information (the item’s arrival time and the value of an attribute called Item arrival), as shown in the cloned table in the model window.
History model
☞ If a History block has been auto-created and placed in parallel to another block, there must be subsequent blocks that can pull the items in. This is discussed at “Pulling and viewing” on page 305.
Discrete Event

   322   323   324   325   326