We use FM458 card to positioning rolls at hot rolling mill.
It works fine, but occasionally strange problem occurs: output position (from NAVMC block) suddenly starts to increase (or decrease) and doesn't stop inspite the motor doesn't move (no impulses arrives from encoder).
Another strange thing is, that output speed from NAVMC block = 0. Sometimes manual motor movement helps to stop this abnormality, sometimes restart of FM card is neccessary.
We have this conditions:
CPU: 416-2 DP
FM cards: FM 458-1 DP (6DD1607-0AA2 ,firmware V2.0, 64bit), 2x EXM 438-1 (6DD1607-0CA1)
Encoders: optical 600 increment encoders with n, n90 and c signals connected to EXM card (negated signals are grounded)
NAVMC inputs: see attached picture
Does someone have a clue, what could be the problem?
Please let me know if you have experience in similar behaviour.
Thanx a lot!