Powerflex 525 directly controlled by HMI

Hello all!

I have a simple motor control cabinet and I would like to update the existing vfd with 525 and add an HMI (probably C-more EA9)

I don’t need to start/ stop from the HMI but I would like to graph / log output frequency and current etc. on the HMI and save as .csv etc

I would like to keep it as simple as possible

Is it possible to do this over Ethernet without adding a plc ?




Thanks
Al
!!

Short answer is yes
Use Modbus communications
I would just use a cheep desk top computer

Welcome to the PLCTalk forum community !

I don't have direct experience with this specific approach and the PowerFlex 525, though my experience with A-B drive communications for older models is very extensive.

I agree that Modbus RTU over serial might be the appropriate method, instead of EtherNet/IP. Here's why.

The applicable user manual for Ethernet is the 520COMM-UM001, for the Embedded EtherNet/IP Adapter in the PowerFlex 525.

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/520com-um001_-en-e.pdf

The PowerFlex 525 does not directly emulate an A-B PLC data table over Ethernet for the whole parameter set. You'll see the "PCCC Object" supports the PLC-3/PLC-5 commands for Word Range Read and Write, but that it only emulates a small portion of a PLC-5 style "N41:x" data table for Start/Stop and Command/Reference.

An A-B PLC or an appropriately capable HMI can still access any parameter in the drive over Ethernet, but it has to use the DPI Parameter Object, not the classic PCCC command set. A-B controllers can do that with MSG instructions, but most third party HMIs cannot. In fact, I don't even know if the PanelView Plus can do that anymore.

Note that above I repeated "over Ethernet". The PowerFlex 525 also has an RS485 serial port that implements "Drive Serial Interface", a superset of Modbus RTU.

So if your HMI has Modbus RTU Master capability, you can access many of the parameters in the drive as though they were Modbus "4xxxx" Holding Registers.

See Appendix C of the 520-UM001 User Manual for the wiring of the DSI serial connector, and the Modbus addressing and function codes.

A ProFace HMI has the ability to control a 525. I do it almost daily. It also has an internal PLC for logic. Lower end ($100 US) models don't have I/O though, just logic.

It's clever that the ProFace devices have an output heartbeat or automatic output refresh. I'd like to know if they use the PCCC Object or some of the other EtherNet/IP objects.

I suppose it will be important to determine what the "output frequency and current etc." specifics are.

On the PowerFlex 525, the PCCC object can only access the Command and Status words, as well as the Reference and Feedback values.

On the PowerFlex 525, I think the "Feedback" is always the output frequency in increments of 0.1 Hz.

The PCCC object cannot access the Assembly Object or the Parameter Object, so you can't read output current, thermal overload percentage, warnings, faults, etc over EtherNet/IP with a device that can only treat the drive like a PLC-5.

Again, if Modbus RTU is available, then the capabilities of an HMI device actually increase.

Ok thanks!

Can you point me in the right direction as far as what software to use etc on the desktop pc.

I am going to attempt modbus coms via the dsi port for now but in the long run it might make more sense to get this on the network.


Cheers , thanks!
A