1756-L61 communication problems

Crittenden

Member
C
Join Date
Mar 2011
Location
Syracuse
Posts
21
I have a 1756-L61 controller and since I added modules and scheduled them I've been having problems going online and message reading from other PLC's any answers would be greatly appreciated thanks.
 
What is the communication protocol? ENET, CNET, DNET, etc.

Which of the racks did you add new I/O? Or are all of them new?
 
Well, its getting harder and harder to guess our way to your configuration. Can you upload a running copy, optionally strip out all of programming (be it ladder or ST or FBD) and post the ACD file?
 
Please use complete sentences to communicate with the Forum. It's disrespectful to ask Forum members to guess at your problem and then just give us sentence fragments.

It sounds to me like you've configured the Requested Packet Interval (RPI ) for the analog modules to be so short that the new data is taking up all your network bandwidth.

Did you schedule the network or did you just add the modules to the ControlNet while online ? Online addition of modules on ControlNet means they have to be put into the unscheduled bandwidth of the ControlNet, which could definitely load the network more heavily than you expect.

It's also possible that the way you've programmed MSG instructions is using up more processor connections or buffers than you intend them to.

Posting the *.ACD file would be ideal if you want people to examine your I/O configuration.
 
Sorry I didn't mean to be disrespectful. My company doesn't want me to send the Project for security reasons, but I think you're right Ken about the RPI connections I have them set at 250 ms and the Controlnet modules are set at 250 ms. One AI module is set at 100 ms, I'll set it at 300 ms and the other Modules higher. I'm going to wait till the 5/31 to try it. I will post if it works Thank you.
 
Sounds to me like with all the I/O you have, I would look at setting the RPI's to prime numbers as well so that the PLC is not communicating to all the I/O at the same time, but rather in phases that are appropriate for your process.
 
Hi Mort81 I will change the RPI times differently like 275, 300,325, 500. In the future we are going to split up the ranks and add Processors.
 
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