Dear all,

I have an intermittent problem on the 321R's spindle motors. The machine is equipped with 2 spindle motors controlled by a single Control Techniques CD750 mkII inverter (only 1 spindle operates at a time).

The motors fail to start or are interrupted mid-operation (the machine axes continue running until the PLC throws an error and a stop command). The fault occurs regardless of motor loading.

The 321's controller shows errors S02 (PLC stop command issued), S0130 (inverter timeout "exhausted"), and xx91 (inverter did not power spindle motor).
The VFD's display does not show any errors - status remains rdy (ready).

I'm worried that the problem is intermittent, the machine might run for several hours without a hitch, then fail to start the spindle on the next operation, or it might happen on the first start-up for the day, as well as mid-operation (very concerning as there is latency before the PLC shuts down the axis drives and we might bend/brake tools, etc).

Has anyone encountered a similar problem? Am I correct in suspecting the inverter, although it does not display any errors? Is it possible that an external/internal trip situation is occurring that is not communicated back to the Rover's controller, nor displayed on the VFD's control box?

Thank you,
N