ck DLCb>> DLC:1, null :) Figure 4.27 The Simulator watch window 68 Validation of Communications Systems with SDL 4.2.7.9 Modifying the SDL model: Rearrange-Ready-Queue To test a special case impossible to simulate with the current Simulator process scheduling, you may want to rearrange the Simulator ready queue. To do that, select Change > Ready Queue and enter successively the queue entry numbers to swap. Here is an example where we have swapped entries 3 and 2: Command : List-Ready-Queue Entry PId State Signals Signal instance AtoB: 1 start state BtoA:1 start state dispatch: 1 start state <<Block DLCb>> Command : Rearrange-Ready-Queue 3 2 Rearranged! Process scope : AtoB:1 Command : List-Ready-Queue Entry PId State Signals Signal instance AtoB: 1 start state dispatch: 1 start state <<Block DLCb>> BtoA:1 start state Then process dispatch will be executed immediately after process AtoB. 4.2.7.10 Modifying the SDL model: variables To change the value of a variable, you must first set the scope to the desired process instance, if it is not in the current scope. For example, to enter 2 into the variable N320cnt in block DLCa, use Examine > Set Scope and select < < Block DLCa > DLC. Then select Change > Variable, choose N320cnt and enter 2. Command : Set-Scope <<Block DLCa>> DLC Process scope : <<Block DLCa>> DLC: Command : Assign-Value N320cnt 2 Value assigned N320cnt (integer) = 2 To change easily the values of complex structures such as arrays, struct or ASN.1 values, the Simulator automatically prompts you for each required field value. 4.3 CASE STUDY WITH OBJECTGEODE The tools and platform used for the exercises are described in Section 1.5. The V.76 SDL model used for this case study is presented in Chapter 3. Interactive Simulation 69 4.3.1 Prepare the Simulator 4.3.1.1 Compile the SDL model A. Download from the Internet (see the ftp address in Section 1.5) or create the SDL V.76 model, and launch the ObjectGeode SDL Editor: double-click the icon v76.pr19 or for Unix type geodedit v76&. B. In the SDL Editor, s