1756-DHRIO Communication

robinyin

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Dec 2006
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calgary
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Hi Guys, I am working on DH+ between two Contrologixs. Each has 13 slots. I put 1756-dhrio in slot 0, and processor 1756-L61 in slot 3. I just put one rung there: ---||----(MSG)---. MSG setup screen is setup as read for one and write for another one. After I finished connecting a cable between and configuring RSlinx for DH+, I can see Ch_A is used for DH+ because I can see another processor on the link by using RSlinx. CH_a OK light is solid green too.

But each time I download the program into the processor, there is module fault: code 16#ff00, Connection Request Error: No connection instance. What does that mean?

Another thing is how to configure the path of CIP read and write? Based on the above system, could you please let me know the exact path for each part. The link ID for one CH_A is 1 another one is 3.

Thanks in advance.
 
You should NOT have that 1756-DHRIO module in your IO configuration. Remove it. The error will go away. This is a common mistake. The only time it should be in the IO configuration is when at least 1 channel is being used for RIO. Just DH+ then remove it.

It does not need to be in the IO configuration. Many people put it there because they do not know how to write the path in the message configuration without it.


You can leave the module in your IO configuration and it will work. It just makes the IO led blink and indicate an error. This is NOT the right way to do it, but I have seen several systems installed by "pros" that are commissioned this way.

RSL
 
The path is easy.

1,0 then select DH+ for your comms format. Enter the channel number and then the node number. Leave link ID's at 0.

I beleive you want a CIP data read. I am not at work and am going from memory. It occurs to me that you might think you need a message on both PLC's to get communication. You need to either read from one or write to it from the other. It is not necessary to do both. Opinions vary on weather reads are better than writes. That is open to debate.

This should work.

Post again if this is confusing. I am in a hurry and typed this really fast.


RSL
 
Last edited:
One more question

Do you mean I can go ahead to use PLC5 Typed Write or PLC5 Typed Read for Message Type when I work on Contrologix Processors? I am using CIP, but it does not work.
 
I have never done a message from one CLX to another using DH+. I have always been on ControlNet or Ethernet. I have always used CIP data table reads and writes for these.

I have done a lot of messages from a CLX to a PLC5 or SLC500 using DH+. I have always used SLC or PLC typed read and write messages for these.

Now your situation is different than I have done before. I think you need to use a CIP data table read or write. Under the communications tab try using the CIP configuration not the DH+. You need to enter the path for it by hand. There is a great document that details the comms paths and how they work. I am going to paste it in here.

When buiding your message path use the following as a guideline to simplify your task:

All paths are of the following form:
x, y

Where x is the "media type" you want to transmit on. This could be the backplane, ethernet, controlnet, serial, or DH+.
Where y is the node or address on that particular media. This could be a slot number, IP address, cnet node address,
serial address, or DH+ node address.

III: Examples:

Let's start at a 1756L1 sitting in a ControlLogix chassis:
path = 1, 5, 2, 100.100.100.100, 1, 0, 2, 24, 1, 10 (each x,y pair has a different color for reference)

Explanation:
Here are what modules this path travels through:
1756L1 in slot 0
to the backplane
to slot number 5, which has an ethernet module there
out onto ethernet
to IP address 100.100.100.100 (which in this case was another 1756enet module)
to the backplane
to slot number 0, which has a 1756CNB module there
out onto controlnet
to controlnet node number 24 (another CNB card in this example)
to the backplane
to slot number 10 (which has a 1756L1 controller)


IV: Other configuration numbers for the "media type"

Now that the path format of x, y is understood, the following lists the possible numbers for x:

1 The backplane
2 Depends on the module this number is used on:
DHRIO out channel A
ENET out onto ethernet
ENBT out onto ethernet
CNB(R) out onto controlnet
Contollers out the serial port
3 Goes out channel B on a DHRIO module


The following lists some possible numbers for Y:
Media you are on: Value for Y:
ControlNet Controlnet Node Address
Ethernet Ethernet IP address
RS232 Serial port DF1 node address
The backplane Backplane slot number
DH+ Decimal equivalent of the Octal DH+ node address
or (8#10) means that the number 10 is in octal.
 
You might have to use the DH+ tab on communications to get this to work. If you do then you will need to set the link ID's of your DHRIO modules using RSLinx. (This is more confusing than the CIP type is)

I would think you could configure it either way, but using the CIP method shuld be the easiest. Maybe one of the experts could weigh in on this.

Please post your results, I am curious.

RSL
 
Hi there have you looked at the DH+ sample project "DHplus_messaging" available in RS5000 It describes both PLC5 messaging (needing the DH+ link numbers set up properly via RSLinx and Mapped Tables) and CIP which does not need link numbers and uses Logix 5000 Tags.
I think that both method are easy to set up but it depends on the rest of the plant and future comms methods that you will use - If existing SLC or PLC5 and they will be around for a while then I would go PLC5 - IF no SLC's or PLC5 then CIP which is easily modified to Control Net or Ethernet.
PS I agree with RSL do NOT put the DH+/RIO card in your IO unless you are using RIO - I hate blinking lights that the shift electrician tries to fix at 2 am for 4 hours when the machine won't go.
 
Well, I have been unable to make the CIP data table read/right work on my test system. I tried everything I could imagine. The example in the sample directory is using DH/RIO C mine are series B. Other than that I can't see any differences. In short, I have been unsuccessful in reading a CLX tag out of one prcessor from another CLX across a local DH+ network using the CIP configuration and paths. I get a connection failure Error code 16#0001 Extended Error code 16#0000_0204

I had no problem using the PLC5 data mapping function and reading the data like it was a PLC 5.

I have no explanation for why it won't work. I hope someone will ring in and tell us.

RSL
 
I have numerous DH+ communications between ControlLogix processors.

Upon initial installation, they were put in using PLC5 messaging. I have since changed them to CIP and all works well.

Have you completed the path completely to the "other" processor? CLX messaging isn't the same as the PLC5 where you just put the DH+ node number.

One other quick thought ... how are you entering the node number? The CLX messaging is base 10, but the DH+ is node base 8. Quick way to enter the node number is "8#[node]" where [node] is the DH+ node number.
 
I think that's it Oakley!!

Hex! I have not been entering my node numbers correctly. I am on the way home. I will try this again tomorrow. I am sure the path and everything else was entered correctly, so I think you hit it.

I knew it should work and could not figure out why it wouldn't.

RSL
 
Yep, it was the node numbers. I was not thinking octal. It says plain as day in several things I have read that the node number is octal.

Thanks Oakley. I was giving advice and felt pretty silly when I couldn't make it work either.

Robinyin, I would use the CIP method. It is the best for CLX to CLX comms. It does work. The example in the samples folder should get you going.

RSL
 
That one stumped us for a while as well. One of those "Once you learn it, you never forget it" Rockwell features.
 
Guys,

Can I communicate with PLC5s that connected to other CLX Bridge? How to configure the communications path and the data type? CIP or PLC read type.
Before, I put this path:
1,2, 2, 142.40.36.48, 1, 3, 3, 41
1=backplane to 2=enbt to 2=out to ethernet to Enet bridge to 1=backplane clx to 3=dhrio slot to 3=out to Channel B to 41= node 41 where the PLC 5 connected.

But the message always connection failure. anyone can help?
 
Is the message originated in a PLC5 or a ControlLogix? If it is a PLC5, then you will have to build a routing table in the DHRIO card. If it is in ControlLogix, verify your path.
 

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