MSG PowerFlex40 22-Comm-D

[MorphuisOGrady]

Hi Guys,

I have an CLX L35CR with 3 1769-SDN's. Am I correct in saying I can only have 4 Bytes Input/Output of polled I/O?

I have 21 PowerFlex40's which I need to message for faults etc. Does anyone know of any sample code on the most effective way to do this?

I remember a project a number of years back with same hardware and the messaging was really slow. If a drive faulted it may have taken 10 seconds for the Message to execute because of the amount of them.

How many VSD's can I message simultaneously?

Any advise on this?

 

[gmferg]

Look at using Datalinks. If you only have a few parameters you want to read from the drive, you can use datalinks to receive the data as fast as the start/stop and speed ref commands. Messaging can be used but, it is much more difficult to setup and is much slower.

I setup my drives to read amps, start inhibits, and last fault code via datalinks and other params that rarely change via messaging (ex. accel time, decel time, max Hz, min Hz, nameplate amps).

 

[Craig Spinharney]

Explicit MSG support

Per Bob Law's latest "DeviceNet Book of Knowledge" (8-8-2008)

"All CompactLogix controllers can use the 1769 SDN for I/O master functionality. Explicit Messaging functions are NOT supported in the L20 and L30 processors, but is supported in all other series B processors. 1769-SDN should be Series B V2.001 of firmware.
L20 and L30 controllers are significantly limited in the amount of I/O data that’s supported.
Only 256 words of I/O memory is available for all modules in the CompactLogix chassis. 34 words of overhead is used for the CompactLogix processor and 76 words of overhead is used for the1769-SDN. That leaves a maximum of 146 words of I/O area for both input and output data to/from the 1769-SDN assuming no other modules in the chassis.
All other Series B controllers allow up to 180 words of I/O data each direction per slot. 1769-SDN should be V2.001 of firmware.
I/O data size limitation of 64 words each direction per node."

NOTE: Bob's using 16-bits/word.

I agree that the Datalinks might be your best bet.

 

[MorphuisOGrady]

My understanding was that PowerFlex 40s do not support datalinks?

 

[LJBMatt]

I've used a lot of Powerflex 40s on Devicenet with the Compactlogix PLCs and the standard polled I/O for each drive is 4 bytes IN, 4 bytes OUT. There are 2 status bits that report back Alarm or Error on the drive itself. Typically I use these bits to trigger my alarm reporting bits and also use an explicit message to try and grab the alarm message number when either of these bits are true. This way I'm not polling the drives with a ton of messages.

 

[MorphuisOGrady]

Hi LJBMatt,

Thats sounds perfect. I'll look into that now. Where do I find information on these Alarmor Error bits? Id it extra drive parameters I need to enable?

 

[LJBMatt]

I believe its in the COMM 22 D manual has the mapping layout. I use that mapping layout to make a UDT. Really simplifies things so I don't accidentally use wrong bits. I'll look for the layout and post a link if I find it.
Look in Appendix D of the manual.
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/22comm-um003_-en-p.pdf
Bits 6 and 7 of the return status word are the Error and Alarm bits. If either of these go true I use an explicit message to grab the alarm value.

 

[Ken Roach]

Morphius, you are correct that the PowerFlex 4/40/400 drives and the 22-COMM-D/E/C do not support DataLinks like the 7-series and older 1336+ drives do.

When I write monitoring logic for PowerFlex 40's I usually follow Matt's principle of only reading Warning or Fault data when the Warning and Fault bits go high.

It's also very important to condition your messaging so it doesn't attempt to send a message to a drive that's been shut down. This often introduces timeout delays that degrade your messaging routine performance to an unusable state.

On one application, I had the logic watch the Fault bit and send a MSG Read to get the Fault code immediately. If the fault code was "Input Voltage Low" (a value of 4) we knew that the drive's circuit breaker had been opened and the DC bus was bleeding down, so we suspended MSG instructions to that drive until it re-established communications with the scanner. We never even had to wait for a communications failure !