The Industrial Raspberry Pi Forum

Hi all,
Hoping for some guidance with a issue I'm having with the RevPi running Node-Red.
Currently I have the RevPi communicating to a Allen Bradley Compact Logix PLC via Ethernet connection, and have setup a timestamp in milliseconds to constantly update to the PLC.
The problem is at regular time intervals, the PLC tag stops updating for about 400ms. While in top or htop, i can see that the instance for Node-Red spikes the CPU quite high, and these spike correlate with the comms 'stutter' I'm experiencing at the other end.
Has anyone experienced something like this before? I'm not sure what the root cause of the issue is, testing so far hasn't yielded any obvious results.

Dear TrentB, what RevPi are you using? Please update to the latest Image which is currently Stretch 03/2019. You can verify the current image with

Dear TrentB,

I think this is probably a problem of Node-Red.
And also there are some discussions about this in internet:
https://github.com/originallyus/node-re ... /issues/67
https://discourse.nodered.org/t/cpu-hogging-to-100/2944
Maybe you can follow this to find some solution.

Hi TrentB,

I am curious - are you using NodeRed to connect to the Allen Bradley? I am hoping to do something similar and was hoping if you had some feedback on what setup you used.

Kind regards
Koen