TuxEip and Powerflex Drive?

[JasonV]

New to PLC stuff, and thought I'd ask if the following is possible before I spend too much time going down a dead-end. I'm trying to remotely control a powerflex 525 remotely via a PC. I downloaded TuxPLC/TuxEip library. The documentation says that TuxPLC works with the following Rockwell devices: PLC5, SLC500, MicroLogix, and ControlLogix. I can successfully connect to the Powerflex (meaning ConnectPLCOverCNET is successful).

Before I spend too much time modifying the TuxEip code to read from the right Powerflex registers, does TuxEip have a chance of working with Powerflex, or is Powerflex hardware completely different from the above supported devices?

 

[Archie]

I can't speak specifically about the Tux library, but for the most part the PC based Ethernet IP drivers use Explicit connections based on commands specific to a particular PLC or device. While a typical drive will use an implicit (IO style) connection for continuously updated IO data.

Typically a PC is not good at an IO connection because that style connection will setup to be updated at a particular rate which is referred to as the requested packet intervalue or RPI. Since the intervals are typically in the 10-50ms range, a PC with a non-determistic OS cannot guarantee a consistent turn around at those rates therefore giving an unreliable communication connection.

Another more common option to do what you want is to use a Modbus driver. I do believe the Powerflex 525 supports ModusRTU through its RS485 port.

 

[dmroeder]

I'd guess that it will not properly communicate to the drive without modification. The hardware shouldn't be an issue, it's probably that the CIP commands for drive connections are not in TuxEip.

That's just a WAG from someone who is not in any way an authority on this. It would be interesting to see what another piece of software does when changing parameters via Wireshark.

I see someone with much more knowledge on the subject is reading the thread, maybe they'll chime in. edit: and he did...

 

[JasonV]

Archie, thanks for your input. The Implicit/Explicit communication is a good point. I think Micrologix uses Implicit comm, which Tux supports, so that difference alone may not be an issue.

Using a MOXA with 485 and controlling via Modbus RTU is another option on my list. Because of the inaccessibility of the drive (in a pressure vessel 14 miles away), I'm trying to reduce the number of hardware components that may fail. Though, if I pursue that option, I'm sure there'll be more posts from me.

 

[Archie]

Do you want to control the drive (start/stop) or just set registers?

 

[JasonV]

Start, stop, change freq.

 

[robertkjonesjr]

I think Micrologix uses Implicit comm,

Micrologix does not support the implicit forms of EtherNet/IP, unless it's very recent. Only the higher end stuff does, like Compact- and ControlLogix.