mitsubishi fx1n 40mt

[ford]

I have a fx1n 40mt and I am runing the Gx developer Fx ver.5 , I have a program that I know works that I loaded into the plc .The plc is in run mode
however I have no output , when I moniter online the rung that I am controling through a screen shows all the conditions to get the output however the coil wil not output. it can be forced on through the plc . so I know my common for the outputs are ok ,and the inputs show up on the plc as well as in the ladder rung.
never seen this before , I changed plc and the same result .the plc is in run mode . I know its has to be something simple that I have over looked any help or ideas would be grand .

 

[The_Wanderer]

Could it be that you have the code inside of a nest? If the MC coil for that nest is not energized, when you monitor the code, you will see exactly what you are describing...

Another possibility would be the use of a true ZRST function-- the output could be coming on, but be reset at the next scan...

Post your code/program, and you may get some better help.

 

[Sergei Troizky]

It may be one of the following:
- The rung is not executed, being within STL or subroutine or bypassed by jump.
If you can force the output on/off and it maintains this status, this is your case.
- Double coil: the rung output device is being controlled somewhere else in the program.
- The rung condition(s) are not really true. Rememeber that you are monitoring the devices status as it is at the end of the scan, not during this rung execution.
- Also, some of the conditions may be false for so short time that you simply cannot monitor this.
- And finally, be sure that the program in the PLC matches the program in your PC.

 

[ford]

Thanks for the help

I found the problem the following morning . I had forced a bit to trouble shoot a new machine this set another bit in the program and prevented it from runing .
thanks for your help