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Search: Posts Made By: drbitboy
Forum: LIVE PLC Questions And Answers Today, 02:37 PM
Replies: 4
Views: 175
Posted By drbitboy
Thanks both of you. Yes, I though it seemed...

Thanks both of you.

Yes, I though it seemed absurd as well, but with Rockwell I thought it was better to ask.

Those manuals are pretty good, a gold standard that makes all others seem like Pb,...
Forum: LIVE PLC Questions And Answers Today, 02:27 PM
Replies: 9
Views: 430
Posted By drbitboy
That makes sense. Thanks!

That makes sense. Thanks!
Forum: LIVE PLC Questions And Answers Today, 02:24 PM
Replies: 4
Views: 174
Posted By drbitboy
I assume this is not a homework assignment: ...

I assume this is not a homework assignment:


The two blocks at upper left implement the Start/Stop Circuit; the output of the ...
Forum: LIVE PLC Questions And Answers Today, 12:29 PM
Replies: 4
Views: 174
Posted By drbitboy
P.S. Which language are you using to program...

P.S. Which language are you using to program LOGO!?
Forum: LIVE PLC Questions And Answers Today, 11:22 AM
Replies: 4
Views: 174
Posted By drbitboy
Welcome to the forum! The way to do this is...

Welcome to the forum!

The way to do this is to separate the goals in the program:


one goal is when to turn a (i.e. any) pump on

On when pressure is at or below 50PSI
Off when pressure...
Forum: LIVE PLC Questions And Answers Today, 10:43 AM
Replies: 4
Views: 175
Posted By drbitboy
Typo in 1756-rm001?

Cf. here (https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1756-rm003_-en-p.pdf#page=87).

The Logix manual says the CTD instruction behaves like this:63754
But I...
Forum: LIVE PLC Questions And Answers Today, 10:33 AM
Replies: 9
Views: 430
Posted By drbitboy
Interesting. Does the PLC get an input, to...

Interesting. Does the PLC get an input, to detect that an E-Stop event has occurred, and react accordingly, because otherwise the PLC might re-start the process the moment the E-Stop is reset?
Forum: LIVE PLC Questions And Answers Today, 10:29 AM
Replies: 22
Views: 786
Posted By drbitboy
+1. an analogous problem has been solved...

+1.

an analogous problem has been solved many times. search the forum for the words tail and spill, and maybe others I can't remember.

If the overshoot is 60lbf when running 100% PWM i.e....
Forum: LIVE PLC Questions And Answers Yesterday, 03:02 PM
Replies: 94
Views: 7,341
Posted By drbitboy
Obviously, but at least we are keeping you...

Obviously, but at least we are keeping you amused, so it's not a complete waste ;).
Forum: LIVE PLC Questions And Answers November 28th, 2022, 06:58 PM
Replies: 94
Views: 7,341
Posted By drbitboy
Look at this section of the last trend...

Look at this section of the last trend posted:63732
In that trend, from 1:14:33 and 1:19:09, the [Percent CV] value dropped from 45%+ to 27% almost linearly over time, which means the PID and the...
Forum: LIVE PLC Questions And Answers November 28th, 2022, 06:28 PM
Replies: 8
Views: 374
Posted By drbitboy
+1. The PC needs to be a server (listens), and...

+1. The PC needs to be a server (listens), and the PLC is the client (sends).


How many alarms do you need to check?

It might be simplest to create a Web API using the S7 Library for HTTP...
Forum: LIVE PLC Questions And Answers November 28th, 2022, 05:44 PM
Replies: 8
Views: 486
Posted By drbitboy
Re-stating what others have said in another form...

Re-stating what others have said in another form ...

In that formula:

- Replace the [Actual Voltage(V)] with the Measured Physical Value (e.g. 2502 for _IO_EM_AI_00).

- Replace the [10] with...
Forum: LIVE PLC Questions And Answers November 27th, 2022, 05:05 PM
Replies: 2
Views: 311
Posted By drbitboy
which RS Emulate is running, 500 or 5000?

which RS Emulate is running, 500 or 5000?
Forum: LIVE PLC Questions And Answers November 26th, 2022, 05:32 PM
Replies: 1
Views: 246
Posted By drbitboy
Can you break up the date into multiple strings,...

Can you break up the date into multiple strings, and then send the strings in sequence?
Forum: LIVE PLC Questions And Answers November 25th, 2022, 08:07 PM
Replies: 94
Views: 7,341
Posted By drbitboy
Here is the PID equation from the SLC Instruction...

Here is the PID equation from the SLC Instruction Set manual: https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1747-rm001_-en-p.pdf#G13.1041550

...
Forum: LIVE PLC Questions And Answers November 25th, 2022, 07:52 PM
Replies: 94
Views: 7,341
Posted By drbitboy
No, it does not indicate an unstable PID. ...

No, it does not indicate an unstable PID.

That behavior indicates backlash or some other form of hysteresis in the process.
_
Forum: LIVE PLC Questions And Answers November 25th, 2022, 07:51 PM
Replies: 94
Views: 7,341
Posted By drbitboy
The control output only changes due to the...

The control output only changes due to the pressure changing in the the pressure vessel. Those pressure changes might be caused by changes in the feed tank upstream of the pump, but the PID...
Forum: LIVE PLC Questions And Answers November 24th, 2022, 11:25 AM
Replies: 3
Views: 286
Posted By drbitboy
The wildcard for some SQL versions is the percent...

The wildcard for some SQL versions is the percent symbol (%).


So [WHERE ]


TEXT3 LIKE 'prefix%'

would select records where the TEXT3 character field started with the string "prefix" e.g....
Forum: LIVE PLC Questions And Answers November 22nd, 2022, 08:56 PM
Replies: 2
Views: 283
Posted By drbitboy
just the obvious: MOV to a data type with more...

just the obvious: MOV to a data type with more (enough?) bits (e.g. float or even BCD), do the add, and hope the result doesn't overflow on the MOV back to UINT.
Forum: LIVE PLC Questions And Answers November 20th, 2022, 07:39 AM
Replies: 4
Views: 663
Posted By drbitboy
https://www.edata.omron.com.au/eData/PLCs/CJ1/W394...

https://www.edata.omron.com.au/eData/PLCs/CJ1/W394-E1-16.pdf#page=310
Forum: LIVE PLC Questions And Answers November 19th, 2022, 07:14 PM
Replies: 94
Views: 7,341
Posted By drbitboy
Yes, I am well aware. But the OP has the system...

Yes, I am well aware. But the OP has the system they have, and there may be no budget for hardware. I hope the insanity of a backlash model, while simple to implement, will instead convince them to...
Forum: LIVE PLC Questions And Answers November 19th, 2022, 09:11 AM
Replies: 20
Views: 1,666
Posted By drbitboy
One of several excellent posts here on the many...

One of several excellent posts here on the many non-automation soft skills (as @Tom Jenkins calls them).

The point of education is to learn how to learn. The rest is in the noise.


For hard...
Forum: LIVE PLC Questions And Answers November 19th, 2022, 08:43 AM
Replies: 94
Views: 7,341
Posted By drbitboy
Another Hail Mary

If there is a pilot valve downstream of the current-to-pressure transducer and upstream of the oil control valve, then it might be a pneumatic valve positioner (see image below; source here...
Forum: LIVE PLC Questions And Answers November 19th, 2022, 01:22 AM
Replies: 94
Views: 7,341
Posted By drbitboy
I don't know if this approach would work in the...

I don't know if this approach would work in the field, but I created a model that takes a CV output as the input, and calculates what the actual valve position would be assuming a fixed amount of...
Forum: LIVE PLC Questions And Answers November 18th, 2022, 07:38 PM
Replies: 94
Views: 7,341
Posted By drbitboy
Is it safe to put someone at the valve with a...

Is it safe to put someone at the valve with a tape measure or ruler or yardstick? You can be watching the trend, so at the time when the CV reaches a peak or valley, and starts one of it subsequent...
Showing results 1 to 25 of 500

 
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