The command acceleration is invalid

This parameter error indicates that the ACCELERATION command parameter was invalid:

Set Bias Drive command:
The ACCELERATION must be less than 20000 millivolts per millisecond in Acceleration Mode 1, and greater than zero in Acceleration Mode 3. If this error occurs, the value will be adjusted to the closest valid value.

P command on a reference axis:

The ACCELERATION parameter is the Reference Acceleration Limit for the reference axis, and must be a valid value. If this error occurs, the P command will be accepted, but it will use the previous Reference Acceleration Limit.

Reference command:

The ACCELERATION parameter is the Acceleration Limit, and must be a valid value. If this error occurs, the value will be truncated.