Studio 5000 One shots, handshake required?

[travispedley]

I have seen HMI programmed to reset the ONS bit. Very sloppy programming. Have even seen programs that use another ONS to OTU an bunch of ONS bits. Really sloppy programming.

Dear GOD WHY?

 

[jstolaruk]

I have seen HMI programmed to reset the ONS bit. Very sloppy programming. Have even seen programs that use another ONS to OTU an bunch of ONS bits. Really sloppy programming.

One shots and latches promote sloppy programming IMO.

 

[Aabeck]

Dear GOD WHY?

Because he could.

Must have been programmed by someone from IT!

 

[Operaghost]

One shots and latches promote sloppy programming IMO.

Just to clarify......One shots are quite useful. Latches, or one shot with latches is what you are calling sloppy, right?

OG

 

[Operaghost]

.....Must have been programmed by someone from IT!

Or by someone that just didn't understand one shots

OG

 

[BachPhi]

I have some odd 'bugs' in one of our machines here and was wondering the following:

View attachment 40202

If 'a' is toggled and b allows 'c' to latch. Is there any instance where 'c' would not latch? This seems obvious but my troubleshooting this large program has lead me to this not always occurring for some reason. Is there limitations on how the rung is scanned?

Thanks,

E

I think your problem is the unlatch condition was true same time with your input 'a' goes high. Need to make sure that does not happen. You dont have to use oneshot. see my example below

 

[Aabeck]

One thing I use as a test - with an online edit add a branch around the OTL and latch another "test" bit that is not addressed anywhere else in the program. If that test bit gets latched but the monitored bit doesn't that means the monitored bit is getting unlatched somewhere. If the test bit doesn't get latched then the line is either not true or not being scanned.

If a ladder is not being scanned when you are online the XIO's & XIC's do turn green if they are controlled elsewhere, or are inputs changing.

 

[jstolaruk]

Just to clarify......One shots are quite useful. Latches, or one shot with latches is what you are calling sloppy, right?

OG

IMO, both can be overused.

 

[mellis]

Bad programming is bad programming. The instructions are not to blame.

 

[daba]

One thing I use as a test - with an online edit add a branch around the OTL and latch another "test" bit that is not addressed anywhere else in the program. If that test bit gets latched but the monitored bit doesn't that means the monitored bit is getting unlatched somewhere. If the test bit doesn't get latched then the line is either not true or not being scanned.

Or use the cross-reference on the "monitored bit" and sort the x-ref by "destructive" to see what else could be writing that bit.... much easier than online editing.

If a ladder is not being scanned when you are online the XIO's & XIC's do turn green if they are controlled elsewhere, or are inputs changing.

The programming software looks at the instruction type and the current value of the tag to determine highlighting, totally irrespective if they are, or not controlled elsewhere.

 

[daba]

Bad programming is bad programming. The instructions are not to blame.

Forum needs a "like" button....

 

[JaxGTO]

Forum needs a "like" button....