Installation manual

Danaher Motion Kollmorgen Appendix C
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 119
Troubleshooting
Several problems can occur with encoder-based systems. The most common
problem is miswiring. The section on system phasing (above), provides the
necessary troubleshooting information.
Miswired Hall channels can cause intermittent problems. With miswired Hall
channels, the motor operates correctly sometimes, but will occasionally not
operate correctly after cycling power. It is very important to physically verify
the Hall effect channels. There is a command in the SERVOSTAR manual
called, "HALLS." It returns the hall code as "read." It is important that the
installation and startup procedures for the machine sequence the motors through
all the appropriate hall codes to make sure they are present and in the right
sequence.
An 'illegal hall code' error occurs if the Hall channels go to all low or all high
conditions. A broken wire or misphased channel can cause this problem.
It is important that the A and the B channels be wired appropriately to the
SERVOSTAR drive to ascertain the correct directional drive information. This
can be verified by displaying the PFB variable while rotating the motor shaft
clockwise. The PFB variable should be counting in a more positive direction. If
it counts in a negative direction, the A and B channels are inverted. This can be
fixed by swapping the A and /A wires from the encoder or by using the MFDIR
command.
A/B Line Break errors may occur and can be misleading. The SERVOSTAR
receives the A/B/I channels in a differential format. Each channel is fed into a
bridge rectifier to create a DC voltage that is monitored for presence. Absence of
any one of these three voltages (except the I channel in MENCTYPE 3,
MENCTYPE 4, and MENCTYPE 6) cause an A/B line break fault.
LINE DRIVERS, RECEIVERS, AND TERMINATIONS
Counting pulses sent over cables going through an industrial environment
requires that care be taken to prevent noise induction on the cable that looks like
an encoder pulse. Running wires in a "clean" raceway is one requirement.
Another common sense approach is to use differential transmission for the
signals to provide the highest degree of noise immunity. Differential line drivers
are required by the SERVOSTAR. The differential line signals follow the RS-
485 format where pulses are sent up and down a 120Ω cable. Termination is
expected at both ends and the SERVOSTAR provides the required termination.
Deviations from a 120Ω characteristic impedance cable when using long cables
can result in poor performance.