In the SDL Editor, unload all files except v76.pr, and select Tools > SDL & MSC Simulator. B. In the ObjectGeode Launcher, remove any file other than v76.pr, press the Build button, then, if there are no errors, press the Execute button. The Simulator starts. 7.4.4.2 Add filters To avoid an infinite number of global states, we need to limit the number of signals present in the input queue of each SDL process. To detect which queues have too many signals, you must type (or put into your geodesm.startup file) define verify_stats true: after interrupting an exhaustive simulation, the Simulator will display the number of states taken by each process queue. For example, in the V.76 SDL model, if you simulate the scenario shown in Figure 7.51, the queue of the instance 1 of process DLC in block DLCa contains four signals. If this process does not input the signals in its queue while other bursts of L_DataReq are transmitted to process dispatch, the number of L_DataReq stacked in the queue will grow rapidly. In addition, each new signal stacked in the queue generates a new global SDL model state during exhaustive simulation. queue_4 inst_1_dlca.dispatch inst_1_atob inst_1_btoa PROCESS/ PROCESS/ PROCESS/ v76test/dlca/ v76test/ v76test/ dispatch(1) inst_1_dlca.dlc datalink/atob(1) datalink/btoa(1) _estabreq(0) PROCESS/ v76test/ dlca/dlc(1) v76frame( sabme : (.0.) ) v76frame( ua : (.0.) ) t320(12.0) v76frame( ua:(.0.) I_datareq( 0,86) I_datareq( 0,86) I_datareq( 0,86) queue of DLC(1) I_datareq( 0,86) in block DLCa I_datareq( 0,86) contains 4 signals I_datareq( 0,86) Figure 7.51 Scenario showing four signals in the queue of an instance of process DLC To prevent such a situation, we use the filter command to limit to one signal in each queue. Note that some models might not work with such a limit, for example, if two signals are transmitted at the same time to a process queue. 232 Validation of Communications Systems with SDL A. In the Simulator, press on the button Verify B. In the Verifying window, press on Limit a queue. 