Siemens / TIA

CTU in TIA will not reset — I swear the R is firing

Jules Parkes · Student · co-op

S7-1200, school cell. Counter counts. Reset coil is green. CV sits there. Lecturer said it should work. I'm on M bits because that's what the handout used. What am I overlapping?

Priya Shah · Integrator
Stop using overlapping M addresses. MW3 and M3.7 live in the same bytes. CTU CV as a word will stomp the bit you think is the reset. Put the counter in an FB instance DB, or at least a dedicated DB, not merkers. Prove it with a one-rung test: count, reset, nothing else. Then add the plant conditions back until it breaks.
Naveen Iyer · TIA trainer
If you must stay in merkers, keep words on even addresses and never share the byte with a discrete. Still a bad habit. Instance data is the whole point of TIA.

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