You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old August 27th, 2017, 05:36 AM   #1
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
Control motor pump with vfd through DMX

Let's say I am making fountain. I use Sunliye Suite 2 to make all animations of lite, including pumps. How could i transfer signal from DMX to controller or may be directly to VFD. I would not like to use analog input on VFD as I think it is not exactly sutable but I would like to use RS485 and Modbus RTU.

Perhaps there is a decoder from dmx to modbus or may be i need dmx controller with buld in modbus?
  Reply With Quote
Old September 11th, 2017, 10:35 AM   #2
rpoet
Member
United States

rpoet is offline
 
Join Date: Jun 2008
Location: New York, NY
Posts: 469
Quote:
Originally Posted by Serhioromano View Post
Let's say I am making fountain. I use Sunliye Suite 2 to make all animations of lite, including pumps. How could i transfer signal from DMX to controller or may be directly to VFD. I would not like to use analog input on VFD as I think it is not exactly sutable but I would like to use RS485 and Modbus RTU.

Perhaps there is a decoder from dmx to modbus or may be i need dmx controller with buld in modbus?

Since no one else has commented, I'll jump in:
There do exist DMX ---> MODBUS RTU modules, but they're expensive, and I've had trouble with vendors even emailing me back re. product inquiries.

0-10V directly into the drive's analog input works just fine; I've done it many times. If you need non-linear scaling and can't do it in the drive itself or in your DMX source, put a PLC with analog I/O in between the DMX -> Analog converter and the drive.

What are your concerns with using 0-10V directly to the drive?

Below is a link to a great source for DMX ---> Analog converters. I've used Northlight Systems gear for years; very robust and the price is right.

http://www.northlightdmx.com/dmx512decoder.htm


-rpoet
  Reply With Quote
Old September 12th, 2017, 12:00 AM   #3
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
Quote:
Originally Posted by rpoet View Post
What are your concerns with using 0-10V directly to the drive?
Here is my concern. I have SCADA or HMI. It is ok to decode DMX directly to 0-10V signal when DMX is playing. I am usinf Sunlite Suite 2. So it is for shows. But there are also times, when I need to run it statically or manually change levels on every pump. This I can do through PLC.

So in my mind I need to conect drives to PLC either through 0-10V analog output or RS485 Modbus RTU, does not matter. The point is connect to controller. Then I read DMX and convert and control drives. When there is not DMX, I simply control pumps though controller manually.

If I use DMX->0-10V decoders, I'll have to have relay on every line to switch signal from DMX to controller. In my view this is unnecessary complication.

I have found one device

https://www.adfweb.com/home/products...pg=products_16

It is around 300 EUR. It is not cheap, but if I have more than 10 pumps, I would need more than 10 DMX->0-10V decoders plus more than 10 relays and that would come about the same price.

I also found out that WAGO and Beckhoff PLCs have a special DMX master module, that is arounf 200 EUR. I might select that controller because of that feature.
  Reply With Quote
Old September 12th, 2017, 10:12 AM   #4
rpoet
Member
United States

rpoet is offline
 
Join Date: Jun 2008
Location: New York, NY
Posts: 469
Quote:
Originally Posted by Serhioromano View Post
Here is my concern. I have SCADA or HMI. It is ok to decode DMX directly to 0-10V signal when DMX is playing. I am usinf Sunlite Suite 2. So it is for shows. But there are also times, when I need to run it statically or manually change levels on every pump. This I can do through PLC.

So in my mind I need to connect drives to PLC either through 0-10V analog output or RS485 Modbus RTU, does not matter. The point is connect to controller. Then I read DMX and convert and control drives. When there is not DMX, I simply control pumps though controller manually.

If I use DMX->0-10V decoders, I'll have to have relay on every line to switch signal from DMX to controller. In my view this is unnecessary complication.

I have found one device

https://www.adfweb.com/home/products...pg=products_16

It is around 300 EUR. It is not cheap, but if I have more than 10 pumps, I would need more than 10 DMX->0-10V decoders plus more than 10 relays and that would come about the same price.

I also found out that WAGO and Beckhoff PLCs have a special DMX master module, that is arounf 200 EUR. I might select that controller because of that feature.
You don't need a card per drive. The link I sent you has an 8-channel card, and a 24-channel card. That will give you setpoints for 8 or 24 drives, respectively.

If you need to switch control sources and you already have a PLC in the system anyway, simply bring the 0-10V analog signals into a 0-10V analog input card(s) on your PLC. Send your speed references to your drives via MODBUS. How you manipulate the speed reference values once they're in our PLC is all up to your program.

I'm wary of those types of converter boxes; they're expensive, and I've had trouble with documentation and programming with those types of devices before. Perhaps that converter you linked to works well, perhaps not. 0-10V is easy to understand and troubleshoot. It also lends itself to replacement and upgrade in the future; what if the supplier for your converter box disappears and the converter dies? How do you quickly get the system up and running again? 0-10V gear is ubiquitous and every vendor supports it.

EDIT: I just tried to download the user manual to the converter you linked to, and the PDF is broken. Case in point regarding bad / no documentation.

Of course, using a PLC that natively supports DMX is a great choice too. Both Beckhoff and WAGO are good choices.


-rpoet

Last edited by rpoet; September 12th, 2017 at 10:28 AM.
  Reply With Quote
Old September 12th, 2017, 12:50 PM   #5
jraef
Member
United States

jraef is offline
 
jraef's Avatar
 
Join Date: May 2006
Location: Northern California
Posts: 1,588
If you are going to have a PLC in between the DMX controller and the VFDs, you can have the PLC communicate with the VFDs over Modbus or whatever protocol the VFDs and PLC have in common.

Also, do you need a true analog speed control of the pump? If you can live with say, 7 or 8 pre-programmed speeds, it can be a lot easier.

Interesting side note: I have used VFDs on fountains using their own internal "step control" functionality and through experimentation, I have found that people can detect repeating patterns of up to and including 5 steps, but only about 1/2 of them can detect 6 steps as repeating and less than 10% can detect 7 steps as a repeating pattern, they think it is random.
  Reply With Quote
Old September 12th, 2017, 01:43 PM   #6
shooter
Member
Netherlands

shooter is offline
 
shooter's Avatar
 
Join Date: Sep 2002
Location: duketown
Posts: 2,659
have a look at arduino as translator.
__________________
shooter@home.nl
skype shooter paul.deelen
Computer Shooter
Paul Deelen
J. Wassenaerstraat 29
NL 5224 GG 's-Hertogenbosch
+31653300739
  Reply With Quote
Old September 13th, 2017, 07:55 AM   #7
rpoet
Member
United States

rpoet is offline
 
Join Date: Jun 2008
Location: New York, NY
Posts: 469
Quote:
Originally Posted by shooter View Post
have a look at arduino as translator.
Here we go again...

An Arduino is a nice toy, but is in no way suited to operating in an industrial control panel. It's not hardened, rugged enough, nor does it have suitable I/O connectors for easy use.

I might accept a Raspberry Pi in a panel, depending on what it was doing - data logging, possibly some non-critical COM's translation, etc... And it would have to be installed in a case.

A Raspberry Pi could work pretty well in this application, actually: USB ---> DMX converter to receive DMX, and a either Ethernet or a USB ---> serial converter to talk MODBUS. That of course assumes the OP has the ability to program and support a Pi.


-rpoet
  Reply With Quote
Old September 13th, 2017, 07:58 AM   #8
rpoet
Member
United States

rpoet is offline
 
Join Date: Jun 2008
Location: New York, NY
Posts: 469
Quote:
Originally Posted by jraef View Post
If you are going to have a PLC in between the DMX controller and the VFDs, you can have the PLC communicate with the VFDs over Modbus or whatever protocol the VFDs and PLC have in common.

Thank you, jraef. This is exactly the approach I had in mind and was trying to suggest. I really wish more PLC vendors supported DMX natively. Beckhoff does, but they tend to be overkill for many applications.


-rpoet
  Reply With Quote
Old September 14th, 2017, 03:58 AM   #9
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
I see. this is how I was planning to do that. I want control VFDs through RS485 over Modbus. The VFDs I am going to use are well documented and I know hot to control them through PLC. I even can change parameters. I can connect VFDs to 0-10V and RS485 and change parameter "Signal source" from analog input to RS485 and back. So when animation show is started I set to read analog input, and when I switch to manual mode, I can change parameter in VFD dynamically and user RS485 as signal source.

The main point for me that animation show is based on DMX and Sunlite Suite 2.

Regarding recognizable patterns I agree if you use reprogrammed tasks. I use algorithm that generate transitions from one level to another (random pump speed) plus time to hold in position, plus number of times to repeat this transition.

At the end I have few repeatable asme transitions but from transition to transition it never repeat. If I have 3-4 VFDs and every one works in this algorithm, you can never detect repetitions of patterns.
  Reply With Quote
Old September 14th, 2017, 07:39 AM   #10
rpoet
Member
United States

rpoet is offline
 
Join Date: Jun 2008
Location: New York, NY
Posts: 469
Quote:
Originally Posted by Serhioromano View Post
I see. this is how I was planning to do that. I want control VFDs through RS485 over Modbus. The VFDs I am going to use are well documented and I know hot to control them through PLC. I even can change parameters. I can connect VFDs to 0-10V and RS485 and change parameter "Signal source" from analog input to RS485 and back. So when animation show is started I set to read analog input, and when I switch to manual mode, I can change parameter in VFD dynamically and user RS485 as signal source.

The main point for me that animation show is based on DMX and Sunlite Suite 2.

Regarding recognizable patterns I agree if you use reprogrammed tasks. I use algorithm that generate transitions from one level to another (random pump speed) plus time to hold in position, plus number of times to repeat this transition.

At the end I have few repeatable asme transitions but from transition to transition it never repeat. If I have 3-4 VFDs and every one works in this algorithm, you can never detect repetitions of patterns.
Serhioromano:

What jraef and I are suggesting is to connect the 0-10V signals from the DMX ---> Analog converter to analog inputs on your PLC. Once you have those value in your PLC, you can switch between using them and other parts of your program for speed reference. Send your speed reference, whatever the source, to your drives over MODBUS.

Do not run your analog signals directly to the VFDs. The DMX ---> Analog card has a common ground reference; tying the ground reference across multiple drives together may lead to strange issues and ground loops.

Bringing the analog signals to your PLC first has several advantages:

1) Shorter analog signal runs. 0-10V signals are subject to noise, so shorter wire lengths, routed away from noise sources, are best.

2) As I said above, you eliminate the possibility for ground loops by not connecting the analog grounds of multiple VFDs together.

3) You can scale or otherwise tweak your speed references in your PLC program. You may not think you need to right now, but having the ability to change scaling electronically (and within the PLC program) will be useful to you at some point.


-rpoet
  Reply With Quote
Old September 14th, 2017, 10:55 AM   #11
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
This is what I want. you are right. The best way is to control VFDs from PLC over RS485. The problem with PLC analog inputs, is price. Analog input modules are expensive. And I have to convert it to analog from DMX. So it meand DMX -> decoder Analog output -> PLC Analog input -> RS485 to VFD. I convert it 2 times. First time from DMX to 0-10 and second itme from 0-10 to RS485. Why?

I think the best way to use DMX -> Serial converter. Somethign like I have already mentioned. To use Beckhoff or WAGO and it's DMX master module. It wil tread DMX signal and convert into WORD variables in controller. So in one DMX universe I'll have 512 variables in PLC. And you avoid all this potential as you call it ground loops.

Another way is to use universal DMX to Modbus TCP converter. Then you conect it directly to controller or add switch if you have additional Ethernet devices. And that is it. You simply read registers from that converter into variables on your PLC.

In my mind if I convert DMX to 0-10 I have to use it on VFD not for further conversion.
  Reply With Quote
Old July 19th, 2018, 11:49 AM   #12
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
My final setup.

1. Sunlight Suite 2 DMX Controller have animation for light and water.
2. DMX to 0-10V converters are cheap and those control VFDs
4. PLC connected to VFD through RS485 Modbus RTU, and on the panel you can switch control from analog signal to RS485. Thus I even can leave light control to DMX and animate water on in PLC. The algorithms for water are much simpler to write in PLC.
  Reply With Quote
Old July 19th, 2018, 03:32 PM   #13
Mad_Poet
Member
United States

Mad_Poet is offline
 
Join Date: Feb 2017
Location: Virginia
Posts: 256
Any chance of posting a U-Tube video of the final product?
Poet.
  Reply With Quote
Old July 19th, 2018, 04:05 PM   #14
GaryS
Member
United States

GaryS is offline
 
GaryS's Avatar
 
Join Date: Aug 2003
Location: Lancaster Pa.
Posts: 816
Check out Yaskawa pump drive
Eliminate the plc altogether you just set the level or pressure using Modbus the feedback goes directly to the drive and the drive dose all calculations ad controls the speed of the motor
Clean simple and cost effective.
  Reply With Quote
Old July 20th, 2018, 12:52 AM   #15
Serhioromano
Member
Kazakhstan

Serhioromano is offline
 
Join Date: Sep 2015
Location: Kazakhstan
Posts: 42
Quote:
Originally Posted by Mad_Poet View Post
Any chance of posting a U-Tube video of the final product?
Poet.
ш have a youtube channel with the same name as my nick here. I'll post review of the control panel and then review of the fountain.

Quote:
Originally Posted by GaryS View Post
Check out Yaskawa pump drive
Eliminate the plc altogether you just set the level or pressure using Modbus the feedback goes directly to the drive and the drive dose all calculations ad controls the speed of the motor
Clean simple and cost effective.
If to use Lenze, it has DMX input module. I can directly use DMX signal to VFD. But i500 Lenze cost arm and leg.
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
Vector control VFD? LowRange LIVE PLC Questions And Answers 7 October 21st, 2016 04:00 AM
Control Speed of VFD using 0-10vdc analog surveypay LIVE PLC Questions And Answers 5 April 7th, 2016 05:09 AM
VFD control lennox1974 LIVE PLC Questions And Answers 7 May 16th, 2011 11:40 AM
Scadapack 350 to control ABB VFD 95ee32069 LIVE PLC Questions And Answers 3 January 5th, 2011 09:22 PM
installing a panelview 600 + rjmarinaro LIVE PLC Questions And Answers 10 June 17th, 2008 12:52 PM


All times are GMT -5. The time now is 11:21 AM.


.