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Search: Posts Made By: Peter Nachtwey
Forum: LIVE PLC Questions And Answers November 25th, 2022, 10:59 PM
Replies: 88
Views: 6,127
Posted By Peter Nachtwey
I don't didn't have enough popcorn for this...

I don't didn't have enough popcorn for this thread. I have one more bag.
Forum: LIVE PLC Questions And Answers November 25th, 2022, 10:55 PM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
So there is a name for doing the obvious. Good. ...

So there is a name for doing the obvious. Good. No one told me what you call this. I was just told years ago that this is what you should do. Someone came up with a name.

This is such a joke...
Forum: LIVE PLC Questions And Answers November 25th, 2022, 01:41 PM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
Is process tracking your term for feed forwards? ...

Is process tracking your term for feed forwards?

Note:
In essence this is "Bump" transfer versus "Bumpless" transfer as in these plots it’s a change of setpoint and then a transition to...
Forum: LIVE PLC Questions And Answers November 25th, 2022, 01:23 PM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
The first equation for CO(s) doesn't look right...

The first equation for CO(s) doesn't look right and you skipped too many steps to follow.


Also, I don't usually combine the whole transfer function into one big function because the control...
Forum: LIVE PLC Questions And Answers November 24th, 2022, 02:10 AM
Replies: 25
Views: 1,449
Posted By Peter Nachtwey
It must be a cultural thing. My name is as...

It must be a cultural thing. My name is as German as German can be but I agree with JesperMP. There shouldn't need to be a selection. The IEC spec doesn't have a case where there are two different...
Forum: LIVE PLC Questions And Answers November 24th, 2022, 01:34 AM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
Excellent! That looks good. I saved your picture...

Excellent! That looks good. I saved your picture because it looks good.
You have made a big leap forward.

The system you and I are modeling is a linearized model of a hydraulic cylinder with a...
Forum: LIVE PLC Questions And Answers November 23rd, 2022, 09:07 PM
Replies: 13
Views: 426
Posted By Peter Nachtwey
There is no info on the devices. The devices...

There is no info on the devices. The devices should have serial buffers so they aren't all driving the lines a once or looking a load all the time. If there are buffers then they should be in a...
Forum: LIVE PLC Questions And Answers November 22nd, 2022, 04:24 AM
Replies: 25
Views: 1,449
Posted By Peter Nachtwey
This makes sense What is wrong with using...

This makes sense


What is wrong with using a timer inside a FB. They are both FBs with static memory to hold state.
Forum: LIVE PLC Questions And Answers November 19th, 2022, 04:40 PM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
[/quote] There are two ways. #1 and...

[/quote]
There are two ways.
#1 and preferred. Fix the wiring. I once was asked to control this
https://www.airporttech.tc.faa.gov/NAPTF
The wiring was poor. They had a 3 Hz filter to smooth...
Forum: LIVE PLC Questions And Answers November 19th, 2022, 04:22 PM
Replies: 88
Views: 6,127
Posted By Peter Nachtwey
@drbitboy, Rube Goldberg would be proud. If...

@drbitboy, Rube Goldberg would be proud.
If what you show is the case, there can be no hope for precision.

Our controllers have controlled valves that use air to move pistons that control the...
Forum: LIVE PLC Questions And Answers November 18th, 2022, 09:46 PM
Replies: 20
Views: 1,618
Posted By Peter Nachtwey
I can relate to that. My first job out of the...

I can relate to that. My first job out of the navy was programming embedded systems. Not PLCs. I said the boss radiated impatientness. Back in 1980 we had 8 inch floppies and 8080 micro...
Forum: LIVE PLC Questions And Answers November 18th, 2022, 01:19 PM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
@#142 What is Process Variable Tracking? Don't...

@#142 What is Process Variable Tracking? Don't you always know where the PV is from the feedback? I can't verify anything since you didn't provide the transfer function for the plant. What I see...
Forum: LIVE PLC Questions And Answers November 16th, 2022, 01:27 AM
Replies: 35
Views: 2,639
Posted By Peter Nachtwey
I don't care about how long they have been a...

I don't care about how long they have been a member of this forum. That is irrelevant. Generally you can tell by the question they are asking and the information they are providing to solve the...
Forum: LIVE PLC Questions And Answers November 16th, 2022, 01:06 AM
Replies: 88
Views: 6,127
Posted By Peter Nachtwey
A trend with the valve position and control...

A trend with the valve position and control output as a function of time is required. Having the actual pressure would be nice too.
Forum: LIVE PLC Questions And Answers November 13th, 2022, 05:26 PM
Replies: 35
Views: 2,639
Posted By Peter Nachtwey
Providing answers is relatively easy compared to...

Providing answers is relatively easy compared to teaching. Teaching requires more back ground and explanation. Sometimes the OP is asking for the contents of a book when this is a forum.


I...
Forum: LIVE PLC Questions And Answers November 11th, 2022, 02:19 PM
Replies: 6
Views: 606
Posted By Peter Nachtwey
Ken has the right idea Obviously the open...

Ken has the right idea

Obviously the open loop gain and time constant while heating is different from the open loop time constant while actively cooling. Therefore there controller gains and...
Forum: LIVE PLC Questions And Answers November 10th, 2022, 10:58 PM
Replies: 32
Views: 2,401
Posted By Peter Nachtwey
I am sure a Aduino can do the basics. However,...

I am sure a Aduino can do the basics.
However, you guys also know that Delta Motion makes motion controllers. I we know how Rockwell, Simens and Modicon test their systems. I looked up the specs...
Forum: LIVE PLC Questions And Answers November 2nd, 2022, 04:49 AM
Replies: 14
Views: 1,167
Posted By Peter Nachtwey
Writing a PID is easy. The SLC500 PID uses...

Writing a PID is easy. The SLC500 PID uses integers. I would use floats.
I don't know what drbitboy means by timing modes. The time between PID executions should be fixed and put in a timed...
Forum: LIVE PLC Questions And Answers November 1st, 2022, 11:44 AM
Replies: 88
Views: 6,127
Posted By Peter Nachtwey
my first assumptions where wrong. It was hard to...

my first assumptions where wrong. It was hard to visualize the system after just the first post. The differential equation that I posted before doesn't apply. After seeing the diagram it is clear...
Forum: LIVE PLC Questions And Answers November 1st, 2022, 11:05 AM
Replies: 14
Views: 1,167
Posted By Peter Nachtwey
Assume you are using timed interrupts. Assume...

Assume you are using timed interrupts. Assume the CV is 0 to 100. The upper limit isn't that important but I will assume the CV range is 0 to 100.
The trick is to accumulate the CV or add the...
Forum: LIVE PLC Questions And Answers November 1st, 2022, 04:55 AM
Replies: 14
Views: 1,167
Posted By Peter Nachtwey
Now how do you do this without a timer but assume...

Now how do you do this without a timer but assume you are executing the PID every 10 ms using a timed interrupt. Think about it.
Forum: LIVE PLC Questions And Answers November 1st, 2022, 04:33 AM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
oops ...

oops
https://deltamotion.com/peter/Mathcad/Mathcad%20-%20T1P1%20CD%20PID%20RK.pdf
Forum: LIVE PLC Questions And Answers November 1st, 2022, 12:08 AM
Replies: 158
Views: 37,345
Posted By Peter Nachtwey
I have Mathcad 13. I can export files in .mcd,...

I have Mathcad 13. I can export files in .mcd, xmcd, and xmcdz which we know you can't read. xmcd files are basically html files.

This is how we calculate the feed forwards gains....
Forum: LIVE PLC Questions And Answers October 31st, 2022, 12:36 PM
Replies: 88
Views: 6,127
Posted By Peter Nachtwey
dP/dt = β(P)*Q(t)/V(t) Where: dP/dt is the...

dP/dt = β(P)*Q(t)/V(t)
Where:
dP/dt is the rate of change of pressure
β(P) is the bulk modulus of air as a function of pressure. Yes it changes.
Q(t) is the net flow into or out of the...
Forum: LIVE PLC Questions And Answers October 31st, 2022, 12:05 PM
Replies: 56
Views: 7,935
Posted By Peter Nachtwey
Oh NO!

log() functions are very inefficient. Two of them are very bad. Hopefully the compiler is smart enough to make log(2) a constant at compile time.

A PLC is very good/fast at testing bits. Brute...
Showing results 1 to 25 of 500

 
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