Communication with Rockwell PLC - messages received 3 times?

Industrial
1

Hello,

I am reading some tags from Allen Bradley PLC. However, I have noticed on debug 1 that I receive the messages with the values 3 times instead of 1 time that I want. Is there any particular reason that this is happening? Can I change it somehow?
I want just to read the tags every 60sec therefore I have specified a cycle time of 60000ms.

Any advice will be helpful.
Thanks.
ETH-IP node

Flow 1
Flow 11075×487 22.9 KB

2

Plus a 3rd screenshot which shows the messages in debug.

Debug
Debug297×568 15.3 KB

3

I don't have that node set specifically. But most node sets like that usually have some kind of trigger node or setup node that controls the triggering of the output. I see the output node goes into a function that outputs to probably a display. I don't see anything in your setup screenshot that shows a timer function. Do you have a separate node somewhere controlling the triggering? Or is there something in another tab of that node's setup that controls triggering? That's likely your problem.

4

Hello,

Many thanks for your answer. This node does not have much configuration to do. I have just changed the cycle time from the default (500ms) to 60000ms hoping that this will do the job. However, there is not documentation that explains what exactly the 'cycle time' means.
Cycle time

5

It seems that it is a known issue with that node. Multiple messages in "All Tags" Mode · Issue #6 · st-one-io/node-red-contrib-cip-ethernet-ip · GitHub

6

Thanks Colin,

I also found this but I was not sure if the problem was fixed as the original post was from 2018.
I understand that the work around the issue is to put a delay after the eth-ip node to implement my 60sec delay?

7

No, configure a Delay node in Rate Limit mode, All Messages, Drop Intermediate Messages with a rate low enough that it lets the first one through and drops the repeats. Maybe set it to one message every 10 seconds for example.

8

Thanks. Make sense.
Already implemented and it is working.

9

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