Double Coils In Logic :

[mechwizard46]

I Am Attempting To Track Down A CC-Link Fault That Is being Called Up By An Internal Coil, Yet Internal Coil Is Not Registering "On".  The Same Internal Coil Is Being Used In Another Program and Works When I Bypass In Logic, But Will Not Activate Via Line Conditions!?! Any Info Regarding This Would Be Greatly Appreciated.

                                                          Bryan

[Steve Bailey]

Whenever I'm troubleshooting faults denoted by bits in a word I look for a place in the program where all faults are cleared by moving a value of zero into the word.

[Parky]

That is a problem with using a coil more than once, It might be how it was supposed to be programmed the problem is that turning on a coil in one segment of the program then using it as a coil in another it may not show the current state, for example, if turned on on the first rung it will be true until a rung with the same coil where it is not. this means it will only be on between the two rungs of code so monitoring it may always show as false & depends on when the coms between the IDE & the plc is done.

See attached, on ladder 1 the bit M1 is on due to M0 being on so ladder 2 counts, however on rung 3 M2 is not on so M1 is off at this point so rung 4 does not count

 

[Gambit]

Are you using GX Works 3 with Dataflow analasis you can find these error more easily.