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Search: Posts Made By: Peter Nachtwey
Forum: LIVE PLC Questions And Answers April 30th, 2021, 11:00 PM
Replies: 10
Views: 840
Posted By Peter Nachtwey
copy the SP to the PV and ramp to the desired SP...

copy the SP to the PV and ramp to the desired SP from there.
copy the control output to the integrator term. Since the SP and PV are equal there will be no change in the control output until the...
Forum: LIVE PLC Questions And Answers April 27th, 2021, 01:11 PM
Replies: 26
Views: 1,620
Posted By Peter Nachtwey
If you want an answer you must provide more...

If you want an answer you must provide more information like how fast, how slow, the mass, how much travel per revolution. This should have been provided on the first post.


I have already...
Forum: LIVE PLC Questions And Answers April 27th, 2021, 02:17 AM
Replies: 26
Views: 1,620
Posted By Peter Nachtwey
Modiconguy didn't say he needed position control....

Modiconguy didn't say he needed position control. If he did I would have suggested using an SSI absolute encoder to avoid needing a homing routine.



A good hydraulic motion controller can do...
Forum: LIVE PLC Questions And Answers April 26th, 2021, 08:08 PM
Replies: 26
Views: 1,620
Posted By Peter Nachtwey
What is your application?

I am assuming you don't really care about position but only velocity as if you are moving a conveyor or feed chain. You don't need to worry about bumping into anything.


This isn't that hard IF...
Forum: LIVE PLC Questions And Answers April 22nd, 2021, 05:10 PM
Replies: 10
Views: 1,004
Posted By Peter Nachtwey
You are going to need something like a security...

You are going to need something like a security camera that records video constantly to a LARGE local storage device. The output should be Ethernet or USB 3.0. You may get by with a webcam and a PC...
Forum: LIVE PLC Questions And Answers April 21st, 2021, 02:41 PM
Replies: 4
Views: 548
Posted By Peter Nachtwey
Is your control panel isolated? We always used...

Is your control panel isolated? We always used an isolation transformer. The isolated side wasn't grounded except that the 0 volt line might have a 1M Ohm resister tied to it keep the isolated 0...
Forum: LIVE PLC Questions And Answers April 21st, 2021, 02:29 PM
Replies: 11
Views: 3,253
Posted By Peter Nachtwey
The thread has come back from the dead.

Yes, both feed forwards and PIDs are used together.
I mentioned having a model above. Normally one is controlling by pH which is non-linear so non-linear gains are required if pH is going to change...
Forum: LIVE PLC Questions And Answers April 18th, 2021, 10:01 PM
Replies: 10
Views: 918
Posted By Peter Nachtwey
Norm, how does that help in estimating the...

Norm, how does that help in estimating the STIFFNESS, torsional spring constant, between the TWO inertias?

Repeating what I said above. I have never seen this calculated. With an RMC you would...
Forum: LIVE PLC Questions And Answers April 17th, 2021, 12:53 PM
Replies: 10
Views: 918
Posted By Peter Nachtwey
You should fear no evil

You can modify the SOPDT system identification program to solve for the two inertias, spring constant and the damping. This assumes you get some excitation data. This system won't be as weird or...
Forum: LIVE PLC Questions And Answers April 17th, 2021, 04:20 AM
Replies: 10
Views: 918
Posted By Peter Nachtwey
Excellent, but I have never seen anybody really...

Excellent, but I have never seen anybody really do it for real let alone a controller for it.
The goal would be to control mass 1 without overshooting. I PID with feed forwards will not place all...
Forum: LIVE PLC Questions And Answers April 16th, 2021, 06:29 PM
Replies: 10
Views: 918
Posted By Peter Nachtwey
The shaft will be like a torsion bar if it twists...

The shaft will be like a torsion bar if it twists due to applied torque. This is kind of like a spring. You should be able to get specs on the shaft for the amount of twist per torque.
you must...
Forum: LIVE PLC Questions And Answers April 15th, 2021, 08:21 PM
Replies: 30
Views: 18,011
Posted By Peter Nachtwey
Cool, but I would have bought a .NET assembly for...

Cool, but I would have bought a .NET assembly for Modbus/TCP because it will be faster when written with C or C++.
Forum: LIVE PLC Questions And Answers April 15th, 2021, 01:07 PM
Replies: 9
Views: 463
Posted By Peter Nachtwey
OK, next questions. Since both Rockwell and...

OK, next questions.
Since both Rockwell and Siemens can export .csv files,
can the order of the data be determined by the programmer?
This is for a tuning application which is done and works but...
Forum: LIVE PLC Questions And Answers April 14th, 2021, 11:18 PM
Replies: 9
Views: 463
Posted By Peter Nachtwey
Reading PLC trend data into python.

It is pretty easy to read data from xml, json or .csv files using python.
Can Rockwell and/or Siemens trends be saved in any of these formats?


Dmroeder probably knows.
Forum: LIVE PLC Questions And Answers April 13th, 2021, 11:17 PM
Replies: 56
Views: 3,760
Posted By Peter Nachtwey
For what? Position, velocity, acceleration. How...

For what? Position, velocity, acceleration. How can I read a mind that is intentionally left blank?






First you must understand the problem.
Forum: LIVE PLC Questions And Answers April 13th, 2021, 09:58 PM
Replies: 56
Views: 3,760
Posted By Peter Nachtwey
Yes, can't you see there is a file called...

Yes, can't you see there is a file called seg1234567
That handles the simple case where all 7 segments are used.
There is also a seg123567 where the commanded velocity is not reached so there is no...
Forum: LIVE PLC Questions And Answers April 13th, 2021, 07:25 PM
Replies: 56
Views: 3,760
Posted By Peter Nachtwey
Did you see the .png above? Each one is a...

Did you see the .png above? Each one is a different case.
I think that qualifies for many.
Forum: LIVE PLC Questions And Answers April 13th, 2021, 06:58 PM
Replies: 56
Views: 3,760
Posted By Peter Nachtwey
You haven't proven otherwise. There are 17...

You haven't proven otherwise.
There are 17 equations and 17 unknowns for just one of the cases listed above.
There are many cases.
Forum: LIVE PLC Questions And Answers April 13th, 2021, 01:55 PM
Replies: 56
Views: 3,760
Posted By Peter Nachtwey
What rules are you guys talking about? There is...

What rules are you guys talking about?
There is one rule that rules them all. The Lyapunov function.
Lyapunov's rule for stability can be used to determine whether the sign of the errors in...
Forum: LIVE PLC Questions And Answers April 11th, 2021, 07:58 PM
Replies: 13
Views: 1,059
Posted By Peter Nachtwey
The 12 volts cigarette lighter socket has limited...

The 12 volts cigarette lighter socket has limited power. I think it is 140 W.
I have a 300 W DC to AC inverter but I must limit the power to about 140W.
Forum: LIVE PLC Questions And Answers April 8th, 2021, 12:13 PM
Replies: 19
Views: 1,296
Posted By Peter Nachtwey
What about the phase relationship between the...

What about the phase relationship between the first and second pulse stream.


I don't think a PLC is the right tool for this job. I would try a Raspberry PI or similar.


I know that if I...
Forum: LIVE PLC Questions And Answers April 7th, 2021, 10:02 PM
Replies: 32
Views: 1,388
Posted By Peter Nachtwey
Units, units, units.

The proportional gain should be 1.33% control output per degree.
The open loop gain ( plant gain ) should have units of degree/ %control output.
However, the Rockwell PIDs seem to do everything in...
Forum: LIVE PLC Questions And Answers April 7th, 2021, 05:14 PM
Replies: 32
Views: 1,388
Posted By Peter Nachtwey
The PLC-5 PID design is poor. The same...

The PLC-5 PID design is poor.
The same questions come up over and over again.
Ron Beaufort use to answer all these types of questions.




And some have auto tuning.
Forum: LIVE PLC Questions And Answers April 7th, 2021, 04:52 PM
Replies: 105
Views: 5,660
Posted By Peter Nachtwey
Yes, I am aware. We have S7-1500s we use for...

Yes, I am aware. We have S7-1500s we use for compatibility testing and supporting S7-1200 and S7-1500 customers.
Fixing the indirect addressing problem and creating ProfiNet were two HUGE advances...
Forum: LIVE PLC Questions And Answers April 7th, 2021, 01:54 AM
Replies: 5
Views: 442
Posted By Peter Nachtwey
You need Dos Box https://www.dosbox.com We...

You need Dos Box
https://www.dosbox.com

We still support the old 984 motion controllers.
Showing results 1 to 25 of 500

 
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