Powerflex Multi-drive mode

I am attempting to perform a "scattered" read of parameters on a Multi-drive setup of 1 PF40 and 4 PF4 drives over EIP from an L23E. The 22-COMM module is mounted to the PF40 and everything is communicating fine over EIP on the implicit exchange. Performing single parameter explicit reads also works fine, but the updates are miserably slow.

Does anyone know if "scattered read" ability is supported on the PF40 and / or on the Multi-drive setup or must I just be doing something wrong? The 22-comm manual nor the PF manuals seem to cover very well the communication to PF4 or 40 drives or Multi-drive mode. They focus more on the series 7/750 drives.

The serial "DSI" link is just Modbus RTU on RS-485 at 19200 baud; a lot of users assume that because it's connected to 100 Mb/s Ethernet that it will be fast. I've done some very specific analyses of the performance of the 22-COMM-E in the past.

It's using most of that bandwidth to service the I/O read/writes for the five drives. I'm not surprised that single parameter reads are slow.

The 22-COMM-E user manual does describe the DPI Scattered Parameter Read and Scattered Parameter Write functions, on page C-27, but doesn't give an example.

If you have an RA TechConnect contract, there is an Answer ID #50148 whose title is "22-COMM, A way to access more than one PowerFlex 4/40/40P/400 parameter in a single MSG instruction". The title implies that it describes the Scattered Parameter Read function.

Hi Ken,
Thanks for some of the info. I should also clarify a few things as well.

At the moment, all of the explicit reads I would like to perform are all addressed to the Host PF40 drive (the one with the 22-comm module on it). It would seem that we should be able to expect better performance with this drive since the parameters aren't really on the RS485.

I have noticed that I can only perform 1 message block function to the 22-Comm module for every complete implicit cycle of the whole network. It takes about 100ms to sample all 5 drives. This is fine and what I was expecting. The problem is, I want 5 additional parameters off of the first drive. This means that each one adds 100ms to my overall "explicit" read cycle. Even with modbus RTU over RS485 it should have a minimal affect on my overall cycle comparativley if the parameters were called for all in one cycle. In fact, in the past I have always just used Modbus rtu over 485. At this stage I am having difficulty seeing the advantage of the 22-comm module.

I dug up the answer document you mentioned. It looks as though it is just in reference to N-files. I wonder if I can do a mapping and have it work.

Thank you for your knowledge!