Experimental Physics and
Industrial Control System

We're seeing communications dropouts that last exactly 1 minute for a modbus connection to a PILZ PLC. It happens irregularly, but more often the more the IOC writes to the PLC. Has anyone seen anything like this?

It has happened with older versions of base and modules, but we're currently seeing it with:

Base 7.0.3

Asyn R4.32

Modbus R2.11

It had been happening about once a day, some PLCs more often than others. A recent software change to keep the Table/Segment registers set to the right values by writing them once a second made the problem happen a few times an hour. The IOC has 3 modbus connections, one for bit read, one for bit write, and one for word read. All 3 stop communicating at the same time, for exactly 1 minute, then all recover at the same time.

Thanks,

Garth