Powerflex 525

I have a powerflex 525 drive and I was wondering if it is possible to control the speed of the drive from a potentiometer as well as through programming via eithernet? I know there are 3 separate start sources and speed references for the drive and right now we are controlling it via ethernet through the programming but are wanting to add a pot to be able to speed it up or slow it down through that as well. the thing is though we want the pot to be a range of 9-20 hz and then when not using the pot the Hz would be 45

I don't believe you can. However, why not put a pot on the PLC that will be controlling the drive? It would have its baseline control that could be indexed using the pot. In other words, lets say you have an analog input to the PLC that basically sets the drive speed. That input could be combined with the input from the pot to set the speed.

IIRC, you can use different speed references but not at the same time. Naturally..

In order to swap between the two, you would need to either select the speed ref source via ethernet or a digital input to the drive.


If your using an AB PLC, you can add a datalink pointing to the speed ref source parameter. This will make it available in your controller tags and you can programatically select which reference source you want to use.

seth350 said:

IIRC, you can use different speed references but not at the same time. Naturally..

In order to swap between the two, you would need to either select the speed ref source via ethernet or a digital input to the drive.


If your using an AB PLC, you can add a datalink pointing to the speed ref source parameter. This will make it available in your controller tags and you can programatically select which reference source you want to use.

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This is correct. You can do it, but not at the same time. The VFD only responds to one speed command source at a time. You can however devise a way to change which source it responds to, either by using a digital input to make that change when a switch closes, or via a command over the Ethernet connection.

You can connect the pot to a PLC AI and use it to trim the speed sent to the drive. If the pot is @ 10v then you just send the EIP speed to the drive and do the scaling down to 0v at your leisure inside the PLC

Based on what you've described, you will be adding an external potentiometer (not using the one on the drive). Therefore, you can just wire it into an analog input on the PLC and write basic logic to accomplish whatever you want. Obviously, you "can't" write 2 values into the drive as it may only take one speed, but you can write conditions in which it would take the potentiometer input and in others an "auto" input.

All that being said, if you have access to an HMI for this system, I'd recommend having an auto/manual selection on the screen. In auto, you run the drive based on conditions of the system and in manual, the operator may enter a value from 0-100% (or 0-60Hz) to control the drive (similar to a pot...)

janner_10 said:

You can connect the pot to a PLC AI and use it to trim the speed sent to the drive. If the pot is @ 10v then you just send the EIP speed to the drive and do the scaling down to 0v at your leisure inside the PLC

Click to expand...

Sounds a little familiar.

Firejo said:

Sounds a little familiar.

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Aye - my scan reading isn't up to much it seems!

I am not sure about the 525 drive but I know on some you can setup the POT as a trim pot
to adjust the set speed above and below the main setpoint the drive will add the 2 references together to set the final speed. it would be similar to dancer position feedback to the drive.
this sounds like what you are tying to do.

janner_10 said:

Aye - my scan reading isn't up to much it seems!

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Great minds think alike! Then there is us

Can you use a HMI in place of the pot?