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We are having a noise or interference on DeviceNet such that the AB, 1756-DNB card shuts down (Bus-Off fault) and has to be re-booted (24 VDC power cycled) to get re-started.
It seem to happen randomly when we start or stop our SEW (MOVIMOT) VFDs (4) that are the only items on the DeviceNet. They appear to be creating High Frequency pulses that are being transferred to the DeviceNet network. We have done all the obvious things, such as having an isolated 24 VDC power supply for the DeviceNet on a Sola XFMR with the PLC power supplies (common grounded). Not run the 480 VAC and DeviceNet wiring together. SEW says we need an additional frame ground (#8 AWG wire) from each of the SEW MOVIMOT VFDs back to our MCP which we have added. We are using AB Flat DN cable which does not have a shield / drain wire.
Please let me know if you have any ideas on how to solve / diagnose this problem.
Thanks.
It seem to happen randomly when we start or stop our SEW (MOVIMOT) VFDs (4) that are the only items on the DeviceNet. They appear to be creating High Frequency pulses that are being transferred to the DeviceNet network. We have done all the obvious things, such as having an isolated 24 VDC power supply for the DeviceNet on a Sola XFMR with the PLC power supplies (common grounded). Not run the 480 VAC and DeviceNet wiring together. SEW says we need an additional frame ground (#8 AWG wire) from each of the SEW MOVIMOT VFDs back to our MCP which we have added. We are using AB Flat DN cable which does not have a shield / drain wire.
Please let me know if you have any ideas on how to solve / diagnose this problem.
Thanks.