Lacthed Memory Turned Off?

[d4rkm4n]

Hi guys.

I'm experiencing a latched memory turned off even all of the contact is still on and trigger the coil.

Anyone familiar with this?

Thanks!

[Crossbow]

Check your program that you are not writing to the coil from more than one place.  The PLC scans top to bottom, so if an output is coded twice, the one at the bottom of the program wins.

[d4rkm4n]

8 hours ago, Crossbow said:

Check your program that you are not writing to the coil from more than one place.  The PLC scans top to bottom, so if an output is coded twice, the one at the bottom of the program wins.

Already did cross reference. The coil is not written by any bits. Any idea?

[nehpets]

Check for something like K2M100, where the M100 in this example represents your latched bits, the example shown actions M100 through to M115, the K2 represents 2 nybbles (2 x 4bits)

also check the used devices list.

are the addresses being written to by a HMI or external equipment?

Edited December 19, 2020 by nehpets

[panic mode]

it could be a whole bunch of instructions that could be responsible. some will only affect one bit, some will do one or more words...

consider posting details like PLC type, software version, cross reference etc. 

on small PLCs (FX) latched area may be fixed, on larger PLCs it may be configurable. 

also you did not post your code so maybe your code is not scanned (MCR?)