61.3. Run Control and Command Execution

As was mentioned earlier in the overview, it is possible for a program using the actions library to initiate command execution in the tcl interpreter that spawned it. Because it is possible to end a run with the end proc, it is possible to force the run state to change. Those running data integrity checker programs in conjunction with the actions library may find this useful. The capabilities of the command execution is much more general than run control. Really, the limit of what can be done is at the limit of what the user can create with the TCL programming language.

One special case that is worth mentioning is when the ReadoutGUI that has been running the program is under remote control by a master ReadoutGUI. There is no difference in the behavior of the actions library for this scenario except that run control operations to end the run are forwarded to the master ReadoutGUI. In this way, there will not be scenarios when a single subsystem of the DAQ has shutdown. If the user chooses to propagate the end run to the master ReadoutGUI (via the EndRun function's argument), then they will be able to seamlessly run their DAQ while enslaved and not enslaved. However, if the user chooses not to forward to the master, they will need to add the following code to their ReadoutCallouts.tcl script to ensure that the local_end proc is defined.

      if {[llength [info proc local_end]]==0} {
        proc local_end {} {