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Old August 31st, 2017, 09:22 AM   #1
FingRed69
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Controlling a PowerFlex 525 VFD over Ethernet

I am programming an AB Compact Logix PLC (1769-L33ER) to control a PowerFlex 525-EENET VFD. I have the following questions:

1. I read on another thread that the "Start" command should be given to the VFD until the "Active" bit becomes 1. The same goes for the "Stop" command which should be given until the "Active" bit becomes 0. Is this true for other commands like forward and reverse or should these commands be given continuously?

2. What information do the DigIn1Active...DigIn4Active, CommFreqCnt, and CommLogicCnt tags tell the PLC?

3. What parameters do you recommend adding to the Input and Output Data in the Module Definition? I currently have output current, fault code 1, and Com Sts-Emb Enet for the Input Data. For output data I have selected only Jog Frequency. This VFD is controlling a conveyor but, I am curious what parameters people find useful/applications of these parameters in the PLC program.

Thanks!
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Old August 31st, 2017, 10:57 AM   #2
Bullzi
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Hi FlingRed69 and welcome to the forum,
I just finished a job with a PF525 so I think I can answer your questions:
1. That recommendation comes from a long time Forum Member Ken Roach. He knows his stuff so what he says, I do. That is how I have my start/stop set up in my program. As for the forward and reverse command I only used a VFD for a pump so it is set for forward all the time. I am pretty sure you can write a 1 continuously to the forward or reverse command.
2. The Digital in tags just let you know if you have a 1 or a 0 on the DI inputs. How you program them in the drive will determine what you do with them. The other items you mentioned I am not sure what they do but they are Bool data type so you will get a 1 or 0.
3. Attached is a snip of what I put in the data links. I also use a explicit message to read the previous 3 faults so I can display that info on a HMI.

Hope this helps get you going. It is actually pretty easy to control a 525 over a network and I have never had a problem making it work.
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File Type: png PF525 Setup.PNG (71.7 KB, 255 views)
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Old August 31st, 2017, 02:24 PM   #3
BlueAltezza
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In my last 525 application I used the Ready bit to keep the Start bit active, but used the Active bit in my stop logic as you described.

It was also a forward and reverse application, so I kept the forward or reverse bit active while I wanted to go in that direction - I also used those bits to trigger the Start bit in a later rung.

For Output data - I've used the Accel & Decel before to adjust from the HMI
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Old August 31st, 2017, 02:52 PM   #4
Helliana
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What i have always done is make an alias tag such as RUN_FWD for DriveName:0.Forward and RUN_REV for DriveName:O.Rev. I use these as I would use a drive run signal on a PF755.

Then I have two rungs to work the stop and start bits.

If RUN_FWD OR RUN_REV is TRUE and DRIVENAME:I.Active is NOT TRUE, turn the start bit on.

IF RUN_FWD AND RUN_REV are NOT made and DRIVENAME:I.ACTIVE is true, turn the stop bit on.

I also add Estop and other safety conditions as well.
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Old August 31st, 2017, 06:02 PM   #5
ASF
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Welcome to the forum! The advice you have already received is good, but just to add my two cents...

Quote:
Originally Posted by FingRed69 View Post
1. I read on another thread that the "Start" command should be given to the VFD until the "Active" bit becomes 1. The same goes for the "Stop" command which should be given until the "Active" bit becomes 0. Is this true for other commands like forward and reverse or should these commands be given continuously?
You should absolutely do that with the start and stop commands, but there is no need to do it with forward and reverse. The reason is, if you give the drive a start and a stop command simultaneously, then it will "lock up" and do nothing until you remove both signals, and then restore just one of them. This can be a problem if you continuously give the start signal, and then switch to the stop signal when you want the drive to stop, because the communications to the drive are asynchronous, which means that it is possible for your stop signal to get sent to the drive before the drive has registered that the start signal has been removed. The drive will stop, but when you go to restart it, it will not restart. By removing the start signal once you have confirmed that the drive has started (and vice versa with the stop), you remove this issue.

This issue does not apply with forward and reverse (or any others that I am aware of), so you should send those continuously to ensure that you always have the correct direction selected.

Quote:
Originally Posted by FingRed69 View Post
2. What information do the DigIn1Active...DigIn4Active, CommFreqCnt, and CommLogicCnt tags tell the PLC?
As above, the DigInXActive tags are just the status of the drive's digital inputs. If the tag is 1, the input is on, if the tag is 0, the input is off.

The CommFreqCnt and CommLogicCnt refer to whether the Frequency and drive start/stop Logic are Controlled by Comms or something else. If the drive is currently using the frequency command given to it via comms, CommFreqCnt will be 1. If it's using a preset speed, or speed from the local pot, or something else, CommFreqCnt will be 0. Likewise, if your drive is currently accepting start/stop logic by comms, the CommLogicCnt tag will be 1. If it's accepting a start/stop signal from the keypad, a digital input, or something else, then CommLogicCnt will be zero. Note that this is not a "fixed" value. I had an application once where for the most part I sent speed and start/stop command via ethernet. So most of the time, both of those tags were "1". But later on I wired a pushbutton into a digital input, and set the digital input function to "jog" and the "jog speed" parameter to a fixed value. As soon as I pressed that button, both of those tags turned off, because it was now receiving a run command from a digital input, and a speed command from a fixed parameter. As soon as I released the button, both tags turned back on.

Quote:
Originally Posted by FingRed69 View Post
3. What parameters do you recommend adding to the Input and Output Data in the Module Definition? I currently have output current, fault code 1, and Com Sts-Emb Enet for the Input Data. For output data I have selected only Jog Frequency. This VFD is controlling a conveyor but, I am curious what parameters people find useful/applications of these parameters in the PLC program.
It's entirely dependent on what your requirements are, but typically I use motor current, motor power, fault code 1 and DC bus voltage for the input data. For the output data I typically use only accel and decel times.
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Old August 31st, 2017, 06:15 PM   #6
MATT116
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Just download the AOI from AB.
Just search add on instructions powerflex 525 in the sample code library.
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File Type: jpg IMG_6140.jpg (36.3 KB, 219 views)

Last edited by MATT116; August 31st, 2017 at 06:24 PM.
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Old September 1st, 2017, 05:29 AM   #7
Geospark
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Just a quick little addition...

A lot of users add the Input Datalink "7 - Fault 1 Code". Another useful one in addition to that, if you can afford it, is Input Datalink "611 - Fault 1 Time-hr". This also gives you a rough timestamp for Fault 1, which may be useful for further diagnosing issues.

Regards,
George
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Old December 5th, 2017, 01:20 PM   #8
poi123
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Quote:
Originally Posted by ASF View Post
Welcome to the forum! The advice you have already received is good, but just to add my two cents...


You should absolutely do that with the start and stop commands, but there is no need to do it with forward and reverse. The reason is, if you give the drive a start and a stop command simultaneously, then it will "lock up" and do nothing until you remove both signals, and then restore just one of them. This can be a problem if you continuously give the start signal, and then switch to the stop signal when you want the drive to stop, because the communications to the drive are asynchronous, which means that it is possible for your stop signal to get sent to the drive before the drive has registered that the start signal has been removed. The drive will stop, but when you go to restart it, it will not restart. By removing the start signal once you have confirmed that the drive has started (and vice versa with the stop), you remove this issue.
Sorry to reopening the thread again,

But i didn't understand how by removing the start signal once the drive has started ( vice versa with the stop) will remove the issue of asynchronous communication with the PF525??
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Old December 5th, 2017, 01:45 PM   #9
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Quote:
Originally Posted by poi123 View Post
Sorry to reopening the thread again,

But i didn't understand how by removing the start signal once the drive has started ( vice versa with the stop) will remove the issue of asynchronous communication with the PF525??
Try reading through this thread: http://www.plctalk.net/qanda/showthread.php?t=113180
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Old December 6th, 2017, 12:58 AM   #10
poi123
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Hello again,

Does this issue happen also in explicit messaging?
How about the HMI tag in the mentioned link, does its value change between two rungs?
In addition, if we send a stop command and the vfd is running then we send on the next a start command the vfd will then stop then start again?
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