Rockwell DH+ Comms

Hi all,

I have a requirement for a Controllogix PLC (DH+11) to read data from a PLC5 (DH+45) via a Controllogix gateway (CHA DH+30, CHB DH+31) over DH+.

The attached document details my configuration of the message instruction & routing tables. Everything looks OK to me but when I execute the message instruction it displays:

Error code: 16#200, Error Text: An unknown error has occurred.

I've tried power cycling the racks etc.

The 1756-DHRIO card in the destination PLC (containing the message read instruction) is V7. The 1756-DHRIO card in the gateway is V6.

Note: Rather than reading the data from the PLC5 into the CLX, if I msg write the data from the PLC5 to the CLX then the required data is transmitted (although the message write instruction does error (hex 37).

Any help would be very much appreciated

Hi Rich - looks as though the R3_S3_DHRIO path spec is incorrect - where is this specified ?

It may be possible to define the path-spec explicitly, using the Port,Destination[,Port,Destination]... method, and not use confusing routing tables at all. It's been a long time since I worked on DH+ comms, and certainly never had to route messages through a gateway DHRIO, but I believe the explicit pathing may work..... Someone on here will surely shoot me down if I'm wrong though

Am I right with the following suppositions....

The MSG Read is in the Controller with the DHRIO in slot 3 ?
The Gateway is in a chassis in slot 1, with Port A at address 30, and B at 31 ?
The PLC5 is node 45 attached to port B on the Gateway ?

If these are correct, you could try the following path specification....

1,3,2,30,3,45

That's
1 - out of the controller (where the MSG is) to the backplane (port 1)
3 - to destination slot number 3 (DHRIO)
2 - out of Channel A
30 - to node address 30 (in the gateway)
3 - out of Channel B in the gateway
45 - to node address 45

According to the DHRIO manual, page 98, this should be possible...

Hi Daba

Thanks for your response. I've just tried your suggestion but without success.

I think the routing tables must be correct as if I try a message write from the PLC5 the data is successfully transmitted to the PLC5.

I'm afraid not

Alan, please post as much detail as you can about your specific application and the error codes you're seeing.

Two ControlLogix controllers can use DH+ to read and write ControlLogix Tags from one another, using a full-length CIP Path.

But when one of the controllers is a PLC-5 or SLC-5/04, then the command will be a PLC/SLC data table read or write, and the CIP Path will only go as far as the DHRIO itself. The DHRIO then uses the Port, Link, and Station values to execute the PLC/SLC data table read or write command.

In that 7-year-old thread, it looks to me like Rich was mixing these techniques, or there was a more exotic problem.

If you'd like to discuss your specific application, please start a new thread (you can cite this one with a hyperlink if you wish) by going back to the main Q&A page and clicking on the [Start A New Thread] green button at the top of the forum.