Good Day,
I am seeing intermittent bUs (communication bus) errors on 3 VFD's simultaneously. These are Yaskawa P1000's with CM092 Industrial Ethernet Cards.
There are Stratix 5700 switches between the drives and the Controllogix 1756-L75 CPU. Happens every day to every week -- intermittent.
Reading parameter F6-98, it indicates a 'connection time out'. I don't understand why I would receive this fault. IGMP snooping and querier are enabled on all switches, if that matters.
I do not have unicast checked but Yaskawa said that didn't matter. Packet time is 100 milliseconds. I welcome any input on what might cause this. One Yaskawa tech said I should set speed to 100 Mbps (now set at 10 Mbps).
Any help appreciated.