%s0008 is ALW_OFF in PLC 90-30 CPU351

jcp

Member
Join Date
Feb 2010
Location
Multan
Posts
369
Hi friends;
I attached a image in which ALW_OFF is used before the MOVE INT Block. I want to ask is this block working or not?
Becuase i think its never working and programmer used it to only confuse the people.
Please i need some explanation from ur guys?
Regards

ALW_OFF.JPG
 
Judging by the partial rung 356, just barely visible in your screenshot, the original programmer planned to move %R02000 to %AQ0001 under some conditions and %R07229 under others. Perhaps he never got around to defining the "other" conditions. Perhaps the "other" conditions turned out to be a problem so he inserted the ALW_OFF contact as a quick method of disabling the rung.
 
Sir;
Yes now i understand that where ALW_OFF is used the rung disable till the programmer delete this instruction or change to ALW_ON. am i right?
 
Unfortunately, some programmers use the ALW_OFF as a programming tool. Here's an old thread I started years ago. In the attached program, ALW_OFF was used to disable multitudes of inputs individually, rather than simply deleting rungs or some other approach.

Here ya go.

I would be very very careful removing those. If your equipment is working properly, the PLC is working properly. Don't disturb it!
 

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