Conditional Breakpoints: Specific Features in FBD/LAD

For an effective use of conditional breakpoints in FBD/LAD you have to note some points:

The RLO and the accu 1 are evaluated like they were found after process of the last line. That means just the last operation that changes the RLO resp. the accu decides whether the condition is fulfilled. If there are ambiguities it is recommendable to look at the network in STL for a short time.

If you have programmed a not evaluated SR/RS-flipflop, the value of the lower input decides about the RLO. But mostly one is interested in the value of the flipflop itself. In this case an assignment at the Q-output shall be programmed. Basically this is valid for all elements with a Q-output.

If you want to query a condition which is not in the RLO anymore at the end of a network, e.g. the upper input of a SR/RS-flipflop, so you have to look at the network in STL and set the breakpoint at the corresponding position. You can switch over to FBD/LAD but you have to note that just the signals are displayed correctly in the monitoring mode, which were executed before the reaching of the breakpoint. Click ‘1 Net’ in the CPU-window, then the process is continued until the end of the network and all signals are displayed correctly.

See also:

Breakpoints