MSG Instruction Giving Communication Error

[LP_337]

Hello all,

I am currently trying to establish a message instruction to pass data from a 1756-L73 to a 1756-L71. My communication path from the fist controller is 1,4,2, IP address, 1,0. When all is set and done it is still giving me a communication failure error. Can someone point me in the right direction? Btw they are both on the same subnet. Thanks in advance.

 

[TheWaterboy]

would need to know more about the path, but mine look like vlanX,2,x.x.x.x,1,0

 

[Operaghost]

Let's make sure we understand the path. Your first controller is using an Ethernet module in Slot 4 in the local chassis and the other controller is in Slot #0 in the remote chassis. Is this right? Can you tell us what Ethernet module you are using in the local chassis? 1756-EN2T, ENBT?

What is the error message you are getting?

One thing you might try, is to add the remote ethernet module and the remote controller to your local controller's I/O Configuration. It isn't necessary, but it can make selecting the path much easier.

OG

 

[Ken Roach]

1,4, 2,IP address, 1,0

That looks correct for an Ethernet module in Slot 04 of the originating controller's chassis, and a CPU in Slot 00 of the destination controller's chassis. The 1's in both places indicate the Backplane port, and the 2 is the Network Port of a 1756-ENxT module.

Make sure that you're counting the slots correctly; the leftmost is 00, so Slot 04 is physically the fifth slot from the left.

You can test the CIP Path and basic connectivity by configuring a message to execute the Get Identity service, which every controller and module can respond to.

That, in addition to recording the actual .ERR and .EXERR error values for the MESSAGE control tag, can help you figure out if the problem is network connectivity, CIP Path addressing, or the syntax/spelling/scope/external access settings for the tag you're trying to read or write.

 

[JaxGTO]

I have one here doing almost the exact same thing. You don't need the first 1. You should start with:
Slot the ENxT your going out 4 (the msg block may even put in the name of the module)
Ethernet port 2
IP Address
Backplane 1
Slot PLC is in 0
4,2,x.x.x.x,1,0

 

[Ken Roach]

CIP Paths are always pairs of [Port, Address] values.

When the 1756-ENxT module in the chassis with your CPU is in the I/O tree (they don't have to be if they aren't being used for I/O !), then clicking on that module to start the path inserts the initial "1, slot" hop into the CIP Path string in the MESSAGE control tag. In fact, if you enter "1, <slot>" manually you will see RSLogix substitute the module name !

But the initial hop to the backplane Port 1, then the 1756-ENxT slot, is always the first hop of the CIP Path when you are using an Ethernet module that isn't built into the CPU. You can't skip that first step to the 1756 backplane.

 

[LP_337]

Thanks for the replies everyone. I am going to attach some pictures today of how I have it setup. It may paint a more clear picture of what I'm experiencing.

 

[LP_337]

Attached are some photos of how I have this setup along with the device names from RsLinx, error codes and IP path. Thanks everyone in advance trying to help me resolve this issue.

 

[Ken Roach]

Thanks so much for those screenshots ! Error code 0x0001_0204 is an ordinary connection timeout.

The CIP Path describes the navigation from the CPU that has the MSG instruction in it to the target CPU.

You described the CIP Path 1,4, 2,IP address, 1,0 in your first post.

The second element in that CIP path means that the 1756-EN2TR in the chassis with the CPU that has the MSG instruction would be in Slot 4. But your I/O tree screenshot shows that it's in Slot 1.

The sixth element in that CIP path means that the target ControlLogix would be in Slot 0. But the receiving -EN2TR is in Slot 0, and I don't see the receiving CPU in that screenshot.

So either you're showing the I/O tree in the CPU that's receiving that message, or you've got the CIP path incorrect.

If the CPU that's receiving this message has an entry in the I/O tree, then just select that object in your Path browse, and the CIP Path will be filled in automatically and correctly.