Always Off Bit

[cardosocea]

@BobB,

This is just my memory playing tricks on me, but didn't OMRON actually have memory positions that were Always ON and Always OFF bits thus avoiding this thread altogether?

This would have been 20 years ago and the PLC wasn't brand new then either.

 

[chelton]

@BobB,

This is just my memory playing tricks on me, but didn't OMRON actually have memory positions that were Always ON and Always OFF bits thus avoiding this thread altogether?

This would have been 20 years ago and the PLC wasn't brand new then either.

@cardosocea
Memory is fine. P_On P_Off.

 

[joseph_e2]

If using ladder and you many horizontal contacts coming away from the left of the rung and you wish to insert a single contact in front of them you basically have to redraw the rung.
if there is a normally on single contact and you wish to insert another single contact it is easy to insert between the always on and the vertical line in the ladder - saves a heap of time.

Ah, gotcha. I haven't seen that limitation before. What threw me off was that the machines where I've seen it done were using S7-300s, which don't have that limitation either. Maybe, being a South Korean company, they were used to using a different platform and just migrated over their usual practices.