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Are You Having Communication Errors in Your Network Architecture?


One of our customers had a recurring issue with a PV+ HMI that would eventually lock up and stop communicating to the PLC after several days. Whenever this would happen, they would cycle power to the HMI and it would come back up and run for several more days until it locked up again. They contacted us for assistance and we reviewed their network architecture layout which included a PV+6 HMI, Stratix5700 managed switch, PowerFlex70 VFD, and several Point IO banks.

Since all looked good in the architecture diagram, we visited the customer to take a deeper look at each device’s communication settings. We saw that all ports on the Stratix5700 managed switch were configured for auto-negotiate speed and duplex which is good so long as the devices connected to each port are configured the same way.

When we examined each device’s communication settings, we saw that they were all set for auto as well except for the PV+. Within the network adapter settings of the PV+, the adapter was hard set to 100MB Full duplex. What happens in this mismatched scenario is the switch will attempt to auto negotiate with the device and they end up only agreeing at 100MB half-duplex. This eventually causes FCS errors and collisions on the network which over time will cause the device to stop communicating.

Cycling power will clear the error counters and thus it will communicate again for some time. Once we reconfigured the PV+ network adapter to auto-negotiate speed and duplex it hasn’t locked up since. To learn how to stop communication errors from happening, McNaughton-McKay’s Technical Support Videos can show you how to setup your IP Address in four quick simple steps.