Ge 90-30

[CENTER]

I was wondering if someone has a few monuments to help me out with this GE program. I have been staring at it for the last hour. This is a web press from the 90s and started giving my customer a problem last week. The problem is with reverse inch, forward works fine. The sequence is like this
1. Depress forward inch button
2. You will get a 4 sec horn Rung 17, 18 and can inch for 10 sec
3. Depress the reverse inch button you should have a pulsing horn and the same 4 and 10 sec. Rung 19
The problem is when they depress the reverse inch you get a steady horn the reverse command to the drive. Rung 7 and after 4 sec you get the inch command to the drive. Rung 21. By the way the folder clutch is disengaged. I can’t see anything in the logic that will pules the horn hopefully someone will have some insight into this. Attached in the PDF is the logic. Thanks for your time.

[Steve Bailey]

There wasn't any attachment.

Has it ever worked correctly?

[CENTER]

Yes I know working on it.

[CENTER]

Yes, it always worked. The problem is this is the only documentation I have and there is no way of knowing if on the install there were changes made. This documentation is from GE as delivered.

[drbitboy]

Originally Posted by CENTER

Yes, it always worked.

does that include the pulsing horn before inching in reverse?

[drbitboy]

%I0001 is inch forward, and %I0002 is inch backward?

[drbitboy]

%I0004 (inverted safe/ready), %I0005 (stop loop status), %I0013 (guard) are all permissives that must be 1 for anything to move?

And %I0006 (web break) is part of an interlock that must usually be 1 but can be overridden by %I0009 (10% speed)?

And those are all combined into %Q0013 on rung 12?

[drbitboy]

but yes, I don't see anything there that would cause the horn to pulse before inching in any direction.

[CENTER]

That's what I see. But every press that has reverse has a different tone or pulse for reverse and I don't think it was added in field unless this was a prototype. Thanks for taking a look I thought I missed something.

[Steve Bailey]

You also mentioned that the inch commands only stay active for 10 seconds, but I don't see a timer for that. There are only two timers in the program, both with presets of 4 seconds.

[CENTER]

Having the same problem with that. How or what is the .10 TRM on rung 17& 19?

[drbitboy]

Originally Posted by CENTER

Having the same problem with that. How or what is the .10 TMR on rung 17& 19?

TMR => Timer, which is actually a counter of time periods

0.10s => Timer resolution per TMR count, configuration parameter of the TMR, i.e. in this case a tenth of a second per count.

PV => Timer Preset Value i.e. the number of timer (0.10s) periods, with the input rung condition continuously True*, that must pass before the timer output changes from False to True, i.e. in this case, PV=40, 40 counts x 0.10 second/count => 4.0 seconds.

* "continuously True" actually means "True when evaluated on every consecutive discrete scan cycle over 40 time periods"

[CENTER]

Gotcha. Thanks for the explanation I had no idear what that was. Still don't know why it's used there.

[drbitboy]

it is an on-delay timer. see here and here, and also look for the string TMR in that PDF for more information.

The timer (TMR a.k.a. On-Delay Timer or TON in other brands) is driven by the state, True or False, of the input rung, like the image below. The key thing to notice in the current situation is that, once the logic to inch forward or backward evaluates to True, that feeds the input rung of the TON the timer starts counting tenth-second time periods, but it does not assign a 1 to the output bit of the timer until it reaches a count of 40 i.e. until the input rung of the TON has been True continuously for 4s. So the logic is

• For the first 4s that the inch logic (%T0002 or %Q0012) is true,
  • The TMR is counting
  • AND
  • the TMR count is less than 40
    • so the TMR output bit (%T0009) remains 0
  • so sound the horn per Rung 18
    • inch logic true (%T0002 or %Q0012 value is 1)
    • TMR output bit value is 0 (%T0009)
• After the inch logic has been true for 4s,
  • The TMR count reaches 40
    • so the TMR output bit becomes 1
  • so stop horn per Rung 18:
    • TMR output bit value is 1
  • and inch the motor per Rung 21
    • %T0009 value is 1
    • inch logic true (%T0002 or %Q0012 value is 1)

[CENTER]

Thanks for the explanation and the manuals.