Control logix and DNet question

Alan Case

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Hi all. I might be missing the obvious but at present I am modifying a control logix program that speaks over devicenet to a powerflex 70 drive. The original program has 2 command words in a user defined data type to control the drive. 1 word is the speed reference and the other word is made of bits, ie start command, stop command, acel rate 1 etc. I cannot find the correlation between the word/bits and the drive. In lesser drives and processors I have just nominated the assembly to use in the devicenet software but I see no similarities here.
Another question, I wish to message via CIP Generic to the drive and set an attribute. To set the path I look in the browse window of the message command and click on the devicenet card. The card is accepted, the path displays as DEVICENET but there is no where that I can nominate the node number I wish to message to. Is this the correct procedure or do I have to manually enter a full path name to the node.
I guess I should read the manuals. Thanks in advance. Alan
 
What is CIP Generic Alan? I have used explicit messaging often before. Is this the same thing?
:confused:
 
Alan,

The Browse is not the equivalent to the RSWho/Who Active that actively browses the networks. In the Message instruction the Browse button simply browses what you have in your I/O config. If the module you want is not in the I/O Config (as it likely will not be over DNET) then you must manually configure the path.

It's a bit of a pain, but once you get the hang of it it's not too bad.

Good Luck!!

OG
 
Alan
I've used explicit messages to some devices in the past. In the 'path' window, after the DeviceNet card I needed to put " ,2,node".

i.e. Dnet_card,2,12 for node 12. Can't remembet what the 2 signifies but I seem to remember AB (eventually) gave me this information.

Hope this helps

pp
 
The Help section for the MSG instruction in ControlLogix has a surprisingly good section on CIP Path selection.

Operaghost was right on describing how RSLogix 5000 can only "browse" in the CIP Path entry as far as things that are in the I/O table. Network devices, you're on your own.

I'll expand on Parrafin Power's answer:

CIP Path entries are made up of sets of two numbers: Port and Address. This Path starts from the CPU's point of view.

For example, to message out of a 1756-DNB in slot 5 to a PowerFlex 70 at Node 12 on the DeviceNet, the CIP Path is:

1,5,2,12

How's that work ? Port 1 is the Backplane, Port 2 is the Network.

So that path goes from the CPU, to the Backplane, to Slot 5, out the DeviceNet port, to Node 12.

1, 5 Backplane Port, Address (slot) 5
2, 12 Network Port, Address (Node) 12

See how they're pairs of Port and Address numbers ? The software does let you browse for your "DNet_Scanner" or whatever you've named the 1756-DNB. That just serves as a stand-in for "1, Slot#".
 
About the PowerFlex 70 I/O image: those drives are set up to be less like the AC Drive Assemblies that the ODVA standard suggests, and more like their A-B predecessors.

The first 16-bit Word is the Command/Status and the second 16-bit Word is the Reference/Feedback.

You can find the arrangement of the Command/Status word in an appendix of the PowerFlex 70 user manual, on pages A-4 and A-5.

An excellent graph explaining the relationship between the Command Word and the actual output frequency of the drive is found on page 3-13 in the description of Parameter 83, the Overspeed Limit.
 
Thanks Ken, you have saved me a lot of research once again. I know the info is there somewhere in the manuals but nowadays the options available in the AB range is so huge, that to find the relevant info takes a while. I don't blame AB, I find the manuals quite good, its just getting to the stage of needing a trailer to carry around all the docs. But I suppose its better than not having the info.
Regards Alan.

PS I didnt get to catch up to you at Automation Fair, the event was huge and hard to find anyone.
 

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