proportional valve control with encoder feedback

pttech

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Nov 2017
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Hello, I am a part-time machine builder that has recently been exposed to the world of PLC controls. I subbed out the controls for my latest project which is a fairly simple feed/cut line for steel cable. My contractor supplied a Click! PLC using discreet outputs to a PWM driver to send a voltage signal to a solenoid valve to set a slow and fast FWD and a slow REV feed. The speeds are set by settings in the driver card. I am currently at the extremely dangerous level of experience where I know how to get into the program and modify it without necessarily knowing what I am doing. My supplier is now busy with other projects and I'm on my own now. I would like to change to a 4-20ma analog output from the PLC to the driver card to allow the speeds to be set on my HMI. I am using a 10 PPR pulse generator for the length measuring input to the PLC. I would like to be able to use this for feed back to the PLC to maintain the set speed under different loads. Is this practically possible with my current PLC? Does anyone have any suggestions for a different approach?
 
Yes this sounds like it can be done with the Click PLC.

http://accautomation.ca/programming/plc-basics/
Click PLC Series (Automation Direct)
System Hardware – Video
Installing the Software – Video
Establish Communication – Video
Numbering System and Addressing – Video
Timers and Counters
– Counter Video
– Timer Video
Compare and Math Instructions – Video
Program Control Instructions – Video
Shift Register – Video
Drum Instruction – Video
Send and Receive Instructions – Video
AdvancedHMI Communiation – Video
Create an Analog Voltage Input Tester for a PLC – Video
Wiring Testing Analog PLC Input Click – Video
Modbus RTU Click PLC Master to BRX PLC Slave Communication – Video

Above is a series that will take you though the possibilities of the Click PLC.

Regards,
 
Thanks for that confirmation. I've been through quite a few of the videos and the example programs, but not all of these.

Looking at the last video your list, are you implying I'm going to need to add a Brix PLC to make this work?
 
Thanks much! More reading! It's been interesting. First it was like learning Russian, but I'm now starting to recognize whole words.
 
Is this a hydraulic system? I think so but I didn't see it called out for sure anywhere.

What is the part number and manufacturer for the valve driver & valve

I have never used a Click but looking around on the Automation Direct site, I don't see any commands for closing a loop. The best I found was an old reference to someone who created a custom routine driven off interrupts for a Click to do closed loop but it was forever ago.
 
Is this a hydraulic system? I think so but I didn't see it called out for sure anywhere.

What is the part number and manufacturer for the valve driver & valve

I have never used a Click but looking around on the Automation Direct site, I don't see any commands for closing a loop. The best I found was an old reference to someone who created a custom routine driven off interrupts for a Click to do closed loop but it was forever ago.

The valve is a Walvoil DPC130 with 4 sections. Only 2 are proportional. Complete part number below.

DPC130/4/BR21-S90-LT/C10-1V8EZ3L1/C22-2HV8EZ3L1.UTUTS60S60x2
/C22-1C8EZ3L1.UTUTS50S50/RF30-SAE-24VDC

The driver cards are PWM Controls Part #PVDR01.
 
I think you have some challenges ahead.

  • I'm not sure the Click has a function set that will easily allow you to calculate velocity from pulses
  • With such a low count encoder, any velocity calculated by any PLC will be very coarse making speed control difficult
  • The click does not appear to have a PID or any other type of close loop function so you will have to roll your own

If you want to make your life easy get a Delta RMC75 controller and a higher resolution encoder to do the closed loop control. You can feed the output from the delta to the prop valve driver so long as you can configure the driver for voltage input.
 
I think you have some challenges ahead.

  • I'm not sure the Click has a function set that will easily allow you to calculate velocity from pulses
  • With such a low count encoder, any velocity calculated by any PLC will be very coarse making speed control difficult
  • The click does not appear to have a PID or any other type of close loop function so you will have to roll your own

If you want to make your life easy get a Delta RMC75 controller and a higher resolution encoder to do the closed loop control. You can feed the output from the delta to the prop valve driver so long as you can configure the driver for voltage input.
Thanks Norm,

I had a 100 ppr encoder originally and then discovered the Click started skipping counts at about 400hz. My length measuring does not require a high resolution so we switched to the lower count.

I will look into the controller you mentioned.

Feel free to PM me about the valve Peter mentioned.

Greg
 
Give me a break! A motion control project on a click?

I will look into the controller you mentioned.
Greg
NOOOOOOO!!!!!!!!!!!!

This will be a tech support disaster waiting to happen.
Wait, we will only sell the RMC75 if pttech promises not to call for tech support.
Wait, we're safe. The RMC75 costs 30 times what a click cost so pttech will not buy it.

pttech, you are trying go make this project happen on a shoe string. What you don't seem to understand is that buying cheap components doesn't make it a cheap project. You will waste many hours of your time and everybody's else's time trying to get something simple to go because your hardware is as cheap as it gets and not right for the job. You will waste much more time/money and our time than the hardware is worth.

Norm is right, with the right valve and feedback a simple system you describe can be running by now but that costs money.

What is wrong with the forum today? Can't anybody see this is crazy? Especially maintaining speed with varying loads with a bad valve and low resolution encoder?
 
Chill

NOOOOOOO!!!!!!!!!!!!

This will be a tech support disaster waiting to happen.
Wait, we will only sell the RMC75 if pttech promises not to call for tech support.
Wait, we're safe. The RMC75 costs 30 times what a click cost so pttech will not buy it.

pttech, you are trying go make this project happen on a shoe string. What you don't seem to understand is that buying cheap components doesn't make it a cheap project. You will waste many hours of your time and everybody's else's time trying to get something simple to go because your hardware is as cheap as it gets and not right for the job. You will waste much more time/money and our time than the hardware is worth.

Norm is right, with the right valve and feedback a simple system you describe can be running by now but that costs money.

What is wrong with the forum today? Can't anybody see this is crazy? Especially maintaining speed with varying loads with a bad valve and low resolution encoder?

Peter, I don't spend a lot of time on forums. But I notice that sometimes people respond to replies without reading the original post. :mad: (Couldn't find emoji with middle finger raised)

It's Friday afternoon. You need to chill. And relax. I'll be sure not to call you.
 

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