Ladder outputs not executing

[Neal Nelson]

I'm having problems with Trilogi 6.14 and a T100MD+ where my ladder outputs are not being consistently executed. For example; if I have two differentiate up calls on the output of a rung, only the first might be called but if I modify the program elsewhere, the might both be called.

This happens for latching and clearing relays and outputs as well.

This appears to be a bug in the ladder compiler I'd say as if a rung is true, *all* outputs must be executed, regardless of what may happen during the execution of that output.

Does anyone know why this may be happening or if it will be fixed in Trilogi?

[support]

There is no report of such a bug. It is likely that the output or relay states trigger by the [DIFU] function may have been changed some where along the way in your ladder program or BASIC program. Remember that if you change any OUTPUT[n] variable it will change 16 bit in a single command and that could have changed the logic state of your OUTPUT or RELAY.

I just did a simple test where Input 1 turns on two parallel [DIFU] relays CR1 and CR2, in the next circuit rung, CR1 will latch OUTPUT1, CR2 will latch OUTPUT 2.

Now everytime the INPUT 1 is turned ON, the two outputs are ALWAYS latched. This demonstrates that the two parallel branches are executing correctly.

[Neal Nelson]

OK, here's a simpler example:

If I have a rung that has a latch and unlatch as it's outputs. There seem to be two issues here:

1. Sometimes the result seems dependent on the ordering of the outputs if they are included in the rung condition. For example if I have a run condition containing x, if I clear x as the first output, the second output doesn't seem to run. This is incorrect as once a rung condition is true all outputs of the rung must be executed. The rung condition should not be reevaluated until the next cycle.

2. Sometimes a second output of a rung isn't run whereas in others it is. In my current code I have some rungs that I have had to split into two as they don't work, whereas similar rungs do in other parts of the code. This seems to change as the surrounding code is modified and I can't find a general pattern as to why.

This behaviour has caused me much confusion and slowed my development down considerably.

[support]

Are you referring to strictly the ladder program or are you suggesting that some custom functions was not executed?

I wrote the following program to test what you mentioned. When I click on input #1, output #1 would turn off and output #2 turns ON, when I click on input #2, output #2 would turn off and output #1 turns ON. It works every time.



Are you able to write a very simple program demonstrating what you have experienced and email to support@tri-plc.com ?