PID Control of PowerFlex 40-E via 22-Comm-E

I have previously setup a PowerFlex 525 via Embedded EtherNet/IP, so that my CompactLogix can send the PID Setpoint, and PID process reference (feedback), for PID Loop control.

Now, I am trying to similarly setup a PowerFlex 40-E via 22-Comm-E. I have similarly set the PID Reference Select, and PID Feedback Select (both to Comm Port), but am not able to find the I/O reference tag in the PLC to actually send this data.

What am I missing? Is this not possible with a 40, and only with a 525?

So you're using the drive's built-in PID controls to set the speed, and just sending the PID setpoint via Ethernet/IP?

If so, I would think you would need to set up the datalinks in the drive configuration menu in Studio 5000. I wouldn't think the defaults would have that (they don't for the 525 anyways.)

rupej said:

So you're using the drive's built-in PID controls to set the speed, and just sending the PID setpoint via Ethernet/IP?

If so, I would think you would need to set up the datalinks in the drive configuration menu in Studio 5000. I wouldn't think the defaults would have that (they don't for the 525 anyways.)

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The data links for the PF40 do not appear to be assignable, like the 525

After speaking with Rockwell Tech Support, I have to send a MSG command to set the PID setpoint/reference (137). Datalink is not available.

The PID Feedback is set (in both PF40 and PF525) by using the FreqCommand I/O tag, scaled 0-100% = 0-60 HZ Freq.

Reference Rockwell Knowledge Base 627551 "PowerFlex 525 send PID setpoint and feedback through Ethernet/IP".

"PID feedback will be written using the drive name:O.Frequency_Command tag name. The scaling of the PID feedback is 0-3600, where 3600 = Parameter P044 [Maximum Freq]. Do not datalink Parameter A460 [PID 1 Fdback Sel]"

Guess I need to go back and fix my 525 application, as well.

Glad you got it figured out. I'm curious though, why do the PID in the drive if you have a PLC available? I've never seen that arrangement before.

rupej said:

Glad you got it figured out. I'm curious though, why do the PID in the drive if you have a PLC available? I've never seen that arrangement before.

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CompactLogix and ControlLogix have crappy PID. I've yet to see it done well. MicroLogix does just fine.

Also, since the PID code is already done for me by the drive, I don't need to re-invent the wheel.

Once I have tuned these drives at this site, I plan to repeat at an other site, removing the PID logic from the PLC.

Roy A. Alderman said:

CompactLogix and ControlLogix have crappy PID. I've yet to see it done well. MicroLogix does just fine..

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This is kind of a tangent, but are you sure you're setting up the PIDs properly in the 5000 series processors? They can be configured to be identical to a MicroLogix, but have many more features. And multiple different PID blocks are available depending on your needs.

rupej said:

This is kind of a tangent, but are you sure you're setting up the PIDs properly in the 5000 series processors? They can be configured to be identical to a MicroLogix, but have many more features. And multiple different PID blocks are available depending on your needs.

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Could you share more info about PID in rockwell please and which one to fits better to control a closed loop of poweflex 525 and external encoder?many thanks