pelly09

Message controllogix to PLC-5 on ethernet and DH+

8 posts in this topic

Hi Guys I need a little help with a message that i am trying to set up in a controllogix PLC to read data from a PLC-5 via ethernet and DH+ We have our PLC's on an ethernet network for remote comms (laptop+wifi). From one of the PLC chassis' on the network we have a DH/RIO card that has a number of PLC-5's connected on DH+. I've read that it is possible to read/write data to/from one of the PLC 5's to one of the Logix PLC's through the ethernet and DH+ networks. I've had a stab at setting up a MSG in one of the Logix to read from a PLC-5. However, i cant seem to get the comms path right to access my PLC-5. If anyone can help i will be most grateful. The detail that i have is as follows: ENBT/A -slot 5 of PLC with MSG (10.60.28.97) ENBT/A - slot 1 of "bridge" PLC (10.60.28.60) DH/RIO - slot 2 of "bridge" PLC Node 67 - target PLC-5 Channel A If any more information is required, just ask Thanks Steve

Share this post


Link to post
Share on other sites
For me, the "aha !" moment with the 1756-DHRIO was when I realized I was sending a MSG to the DHRIO module itself, which it was processing on DH+. I'm not sending a message all the way to the PLC-5. So the Path should be something like: 1, 5, 2, 10.60.28.60, 1, 2 CIP Paths are made up of pairs of numbers: a Port and an Address. Port 1 is the backplane, Port 2 is the first network port, and Port 3 is the second network port (on devices like the DHRIO or an old CompactLogix L30). "1, 5" means "out the Backplane port, to Slot 5" "2, 10.60.28.60" means "out the Ethernet port, to an IP address" "1, 2" means "out the Backplane port, to Slot 2" The DHRIO module in Slot 2 is actually processing the message. It's receiving a message configured to use Channel A and targeted to DH+ local address 67. Remember that the leftmost slot of a ControlLogix chassis is Slot 00.

Share this post


Link to post
Share on other sites
Surely that path is incomplete Ken... Shouldn't it have 2,{node}, or 3,{node] on the end to route the message to the node number from either of the front ports of the DHRIO module ? Just sending a message to the DHRIO module can't target the specific node on the DHRIO network. Or am I missing something..

Share this post


Link to post
Share on other sites
I could be wrong about this; it's been a while since I did it. But the idea is that the CIP Path only takes the message over CIP networks (EtherNet/IP, ControlNet, 1756 Bus) as far as the DHRIO module. The DHRIO module then processes it with the arguments you set: the Channel number and Target Node. If it's a Remote DH+ message it also needs the Remote Node and the Local/Remote Link IDs. When the DHRIO module gets a reply from the PLC-5 controller on DH+, it then sends the reply data back over CIP to the originating ControlLogix. So the message transport and handling protocol is CIP all the way to the DHRIO, then PCCC over DH+, then CIP on the way back. I don't know if you can send CIP messages from ControlLogix to ControlLogix by specifying the DH+ port and node. I haven't had to deal with that in a few years. Hopefully Steve can tell us more about what sort of error messages he gets, or other information about how the message isn't working correctly.

Share this post


Link to post
Share on other sites
Ken First of all, thanks for the initial reply. I managed to find time to put the message into my program earlier in the week and bar a couple of minor hiccups I got it working just as it should have. I put the path in as you had stated but had to add a couple of details on the communication tab, hopefully as shown in the images below. These are shots from the actual message working. The first part of the path....1,5 has been replaced with the name of the ENBT/A card....MSI. Thanks for the help that you have provided for me with this Steve

Share this post


Link to post
Share on other sites
That has jogged my memories, it's been a long time since I worked on DH+, but all of what you said now makes absolute sense - DH+ networks don't support CIP, so the embedded PCCC information is used by the the DHRIO module to forward the message to the desired destination. I'm finding that nowadays the more I learn, I forget twice as much :(

Share this post


Link to post
Share on other sites

I am trying to read PLC5 data through Ethernet ip bridge module 1756-ENBT/A by msg instruction. Can any one help for resolving this.

 

Share this post


Link to post
Share on other sites
4 hours ago, PrasannaMadival said:

I am trying to read PLC5 data through Ethernet ip bridge module 1756-ENBT/A by msg instruction. Can any one help for resolving this.

 

Starting a new thread is the best, first step.  Please post screenshots of where you are having issue and what you have tried so far.

Delving into the research...page 13/32, the dated PLC-5 is limited to 16-bit integers, refer to page 16  http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm012_-en-p.pdf

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now