PF527 Control Sync Alarm / Module Sync Alarm

3 posts in this topic

Posted (edited)

Hello Sirs!

I have a problem with PF527. I get alarms 'control sync alarm' and 'module sync alarm' occasionally. I suppose this meaning that PLC is missing some data from the PF527 device. How to confirm this or what should I do with the problem? Any ideas?

Motion group update period is 8ms.

Also this device is the last device in the ethernet line. I am thinking to pull the cable directly to the switch near PLC. I am not sure does it help?




Edited by Jiggadoo

Share this post

Link to post
Share on other sites

Any time I've had a module sync alarm it's been related to the communications between the controller and the module. I assume that you're having an intermittent problem, and that you do get some use of the drive between faults? If so, then this is most likely a communications issue, and not a module configuration / mismatch issue. This is further indicated by the module connection faults displayed at the end of a string of sync and connection faults. 

Pulling a different cable to a closer switch could help. But first check the cable route you're currently using (and the alternate route, if needed) for EMI. Make sure you're not running parallel to higher voltages, other VFD or servo drives & cables, welders, radio equipment, etc. In RSLinx, right click on the 527 node and go to the Port Diagnostics tab of the Module Statistics box and see what your in and out errors are. Getting a lot of those is usually an indicator of EMI, and could cause sync issues if it's that bad.

You might consider using a managed or lightly managed switch. Ethernet is typically limited to 300 feet but even if you're well under that, if you have a lot of nodes on your network, comms can be greatly effected. The managed switch would regulate the CIP traffic between nodes and prevent data collisions, which could also result in the loss of comms you're experiencing.

In the controller that owns the 527, you can go to the connections tab of the 527 properties and try raising the RPI a bit. This will reduce the frequency at which the controller is polling the drive for data, and that might help. So if you're currently updating at 8ms but it takes between 7 and 11ms for each CIP, you'd get an alarm every time it went over 8. However, the tradeoff is the drive might not be as responsive because if you raise the RPI, you increase the comm time intervals between the controller and the 527. It can be a bit of a balancing act between performance and comm faults. 

1 person likes this

Share this post

Link to post
Share on other sites

Fixing the physical cables and connectors seems to help. Looks like problems were in a bad net. After the fixing net, I have not been problems anymore.

Good advices!!!

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now