SLC 5/05 1747-L551C ethernet communications to ABB VFD

[Robb B]

Hello, I've got a project where I need to get information from two ABB ACS880 VFDs onto the plant operator's screen (or alternatively, onto panelview HMI). I've been reading through the ABB and Rockwell documentation, and I think I've come to the conclusion that the SLC doesn't support the communication that I need. I came across this note in the ABB reference: "NOTE! RSLogix 500 and the PLC processor must support Class 3 messaging." I can't find anything that specifies which class of messaging the SLC 5/05 supports, though the EEM instruction has a field which allows you to specify a class (are they referring to the same classes?: "Class (hex)/(dec) - Possible Classes are 0 to FFFF (hex). See Volume 1 of the CIP Common Specification for the list of defined Classes." I haven't been able to find the CIP Common Specification on Rockwell's library.

Plan B is to bridge the SLC and ControlLogix networks (currently separate) so I can use the ControlLogix PLC's to communicate with the VFD's, though that goes through a wireless bridge which also handles a bunch of other data, so I have bandwidth concerns.

Plan C is to try using Ignition's 3rd party Ethernet driver but I think that route would involve a LOT of low level ethernet programming, something I don't think the customer wants to pay me to learn.

Has anyone done something similar? Any suggestions? Anything need clarifying or expanding?

[mylespetro]

I'm not exactly sure if this is conclusive for the SLC, but I have done communication between a MicroLogix 1400 and ABB drives using MSG instructions with no issue. From what I understand, the Micro1400 and SLC are very similar in architecture, but there could very well be a difference in how they handle messaging or Ethernet comms, so I'll defer to some of the people on here who know a bit more of the low-level differences. If it is possible, the ABB website actually had some great example programming (in both .RSS and PDF forms) for the communications. If you get to that point, I can even provide my programming to you to use as a reference.

One caveat was that in my application, the drive had a FENA-21 option module installed, which if I recall correctly is just a separate Ethernet/IP adapter.

[Robb B]

myles, I do have those references from ABB, that's where the warning about class 3 communications comes from. The SLC MSG instruction does not use MG files, the MicroLogix do. The MSG instruction in SLC looks different than the MicroLogix instruction on the setup screen.

[sigmadelta]

How about Plan D: upgrade the SLC 5/05 to a CompactLogix or ControlLogix CPU? That would require changing the driver and tags of the HMI(s) communicating to the SLC as well though. You can use a 1747-AENTR to replace the CPU and keep the existing SLC I/O.

[Robb B]

Originally Posted by sigmadelta

How about Plan D: upgrade the SLC 5/05 to a CompactLogix or ControlLogix CPU? That would require changing the driver and tags of the HMI(s) communicating to the SLC as well though. You can use a 1747-AENTR to replace the CPU and keep the existing SLC I/O.

There isn't much room in the cabinet to add a compactlogix, and there's a LOT of tags to change on the HMI, though I guess a find/replace would probably get most of them. The company is going to have to upgrade the 3 SLC's (a third one runs the tank farm) in the near future, but this project can't wait until then.

Looking more and more like going with plan B.

[joseph_e2]

I'm not 100% sure it refers to the same thing, but I found this article that says Class 1 messaging is the implicit messaging you'd get by adding a module to the IO tree of a Logix 5000 PLC while class 3 is explicit messaging using a MSG instruction.
https://www.rtautomation.com/rtas-bl...ss-complexity/
If that's what ABB is talking about, then you should be able to message with a SLC 5/05.


Here's a tech note (Access level: TechConnect) that seems to say the same thing:
https://rockwellautomation.custhelp....1277/loc/en_US

[Ken Roach]

Do you expect to perform start/stop/speed control on those VFDs from the SLC-5/05, or just read status and diagnostic data ?


Which exact EtherNet/IP interface module do the ACS880 drives use ? ABB has had EtherNet/IP modules for years but it's easy to get confused between the various F-series, R-series, and N-series modules.

If your SLC-5/05 supports EEM instructions, you should be able to read and write ABB drive parameters using their Drive Parameter Object, class 0x90.

[Robb B]

From the SLC instruction manual: "Ethernet/IP Explicit Message instruction for the SLC 5/05 processor (requires series C, FRN 10 or higher OS firmware)." This seems to support your information, joseph.

[Robb B]

Originally Posted by Ken Roach

Do you expect to perform start/stop/speed control on those VFDs from the SLC-5/05, or just read status and diagnostic data ?


Which exact EtherNet/IP interface module do the ACS880 drives use ? ABB has had EtherNet/IP modules for years but it's easy to get confused between the various F-series, R-series, and N-series modules.

If your SLC-5/05 supports EEM instructions, you should be able to read and write ABB drive parameters using their Drive Parameter Object, class 0x90.

At the moment, just read status and diagnostic. Would like to get speed, power, amps, and flow if possible.

The Drives use FENA-21 ethernet modules.

Where did you find that class object number? I haven't found anything that details the classes yet.

[Ken Roach]

I'm working from the User Manual that covers the FENA-01, -11, -21 modules:

https://library.e.abb.com/public/d6a...21_UM_E_A4.pdf

The Drive Parameter Object (Class 0x90) is explained starting on Page 239, in Section E.

You will need to use the EEM instruction in the SLC-5/05. ABB doesn't emulate SLC-500 data tables the way Rockwell drives do.

ABB uses "XX.y" parameter numbering, where XX is the Parameter Group, and the ".y" value is the Parameter. They implement that in their CIP object by making

XX = Parameter Group = Instance
.y = Parameter Number = Attribute.

So to read the Output Frequency (parameter 01.06) of an ACS800, you would use Class 0x90, Instance 0x01, Attribute 0x06.

There may be other ways to read a group of data (an Assembly) with a single message, but I am not (yet) familiar with it.

[Robb B]

Originally Posted by Ken Roach

I'm working from the User Manual that covers the FENA-01, -11, -21 modules:

https://library.e.abb.com/public/d6a...21_UM_E_A4.pdf

The Drive Parameter Object (Class 0x90) is explained starting on Page 239, in Section E.

You will need to use the EEM instruction in the SLC-5/05. ABB doesn't emulate SLC-500 data tables the way Rockwell drives do.

ABB uses "XX.y" parameter numbering, where XX is the Parameter Group, and the ".y" value is the Parameter. They implement that in their CIP object by making

XX = Parameter Group = Instance
.y = Parameter Number = Attribute.

So to read the Output Frequency (parameter 01.06) of an ACS800, you would use Class 0x90, Instance 0x01, Attribute 0x06.

There may be other ways to read a group of data (an Assembly) with a single message, but I am not (yet) familiar with it.

Awesome, thanks!

[Robb B]

58 words for each EEM instruction, and it looks like a separate EEM for every word (parameter value) that I want to read. So if I want to get 5 parameters, I have to use 3000 words of memory. Nuts.

[plvlce]

Originally Posted by Robb B

58 words for each EEM instruction, and it looks like a separate EEM for every word (parameter value) that I want to read. So if I want to get 5 parameters, I have to use 3000(?!) words of memory. Nuts.

Think you might have shifted the decimal point there.

[Robb B]

Originally Posted by plvlce

Think you might have shifted the decimal point there.

oh dang, I did. Not quite so bad then, but still a big memory resource hog.

[Ken Roach]

The SLC really is fairly efficient on memory use, but yeah, the data that configures a message instruction on Ethernet is relatively bulky compared to a small payload.

Take a look at what the FENA manual calls a "Transparent 32 with two assembly plus drive parameters" object.

That might give you the ability to read the drive status plus a block of assorted parameters all at once, with a single EEM message instruction.