Created Date: October 26,2019

Created by: coda87

Pretty simple question... Can't figure out what's happening here.

I have a three position switch wired to a click PLC. The switch is a "return to center " selector switch. Middle position has no contacts, and each left & right positon both have a NO contact wired to an individual input on the click PLC.

In position "JOG ".. I want to turn on a relay ONLY when the switch is held in that position.

In position "RUN ".. I want to turn on a relay and keep it on even if the switch is released

I am using the OUT command for the JOG input to turn on the relay only when the JOG switch is active, and the SET command for the RUN input to turn on the relay and maintain it on when run is active.

However, RUN does not seem to turn on the relay? If I change both of the lines to be SET commands, it works fine (but in JOG, it stays active even when the switch is released, which is not the desired operation).

I assume I need to have a reset command somewhere in here to reset the relay after the set command from the JOG position. But where would that go in here?

Simple program.. screenshot here: https://ibb.co/cXJkcVH

Created Date: October 26,2019

Created by: Adisharr

Like John mentioned, the OUT command works differently than SET or RESET. You never want to use more than one OUT on the same bit. SET and RESET can use the same bit in multiple paces but that can also be a catch in larger programs when trying to figure out how it works.

See if this example makes sense:

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Created Date: October 28,2019

Created by: kewakl

When the rung with the output is determined to be true, the PLC writes a 1 value into an Output Image Register. If a subsequent rung causes a 0 value to be written into the same output location in the Output Image Register., it writes over the results from the first rung. At the End of the scan, the last entry into the Output Image Register. is sent out to the actual hardware output.

Or, Last (scanned) Rung Wins.

Forum admin, FIX THIS!

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Created Date: October 29,2019

Created by: Huff360

Or, Last (scanned) Rung Wins.

Is it considered bad practice to call the same output in multiple sub-routines so long as you would only call 1 subroutine at a time?

If so, what is the best practice for doing something like that? Activate two distinct C bits from the two subroutines, then OR the two bits to drive the coil in Main (or another sub you call each loop)?

Thanks!