C Axis Motor Overload

[Paul Petersen]

Looking for suggestions. This message (overload) is easily cleared, and production resumes.
1.) It is random, sometimes going 3 shifts or more before occurrences.
2.) The program code is using S.1 and S.2 commands.
3.) I have replaced the inverter (Yaskawa G2) with an Advanced Motion Control unit.
4.) Checked connections on card 14
5.) Replaced spindle encoder earlier this year.
6.) Checked motor resistance.
I can't seem to generate an overload by MDI of speeds and belts. It happens when running programs, and randomly so. Thanks.

[Paul Petersen]

Update-moved the spindle command onto a line of its own (ex-M3 S3000.2) the machine ran uninterrupted for the evening shifts. Is there a setting in the control,like look ahead,that is effecting the spindle getting the command, and having enough time to respond, before the control moves onto the next block? A low voltage in the command signal for this new(er) drive?