Chapter 2. Troubleshooting
2 9
Common Problems & Solutions
N O T E
Some software-related causes are provided because it is
sometimes difficult to identify a problem as either
hardware or software related.
Problem
Cause
Solution
Communication
(serial) not operative,
or receive garbled
characters.
1. Improper interface connections or
communication protocol.
2. Serial communication is disabled.
3. In a daisy chain, the unit may not be
set to proper address.
1. See
Troubleshooting Serial Communication section below.
2. Enable serial communication with the
E1
command.
3. Verify DIP switch settings (see page 6), or proper use of
ADDR
command.
Direction is reversed.
(stable servo
response)
1. Command output (CMD) connections
and feedback device connections or
mounting are reversed.
1. Hardware remedy: Switch CMD- with the CMD+ connection to the drive
(if your drive does not accept differential outputs this will not work). You will
also have to change the feedback device wiring or mounting so that it counts in
same direction as the commanded direction.
Direction is reversed.
(unstable servo
response)
1. Not tuned properly.
2. Phase of encoder reversed or
mounting of ANI input is such that it
counts in the opposite direction as the
commanded direction.
1. Refer to the tuning instructions in the
Servo Tuner User Guide or in
Appendix A.
2. If encoder feedback, swap the A+ and A- connections to the OEM6250. If
ANI feedback, change the mounting so that the counting direction is reversed.
Distance, velocity, and
accel are incorrect as
programmed.
1. Incorrect encoder resolution setting.
1. Match the
ERES
command setting (default
ERES
setting is 4,000
counts/rev) to match the post-quadrature resolution of the encoder.
ERES
values for Compumotor encoders:
E Series:
ERES4000
SM Series Servo Motors:
SMxxxxD-xxxx:
ERES2000
SMxxxxE-xxxx:
ERES4000
OEM Series motors (servo):
OEM2300E05A-MO:
ERES2000
OEM2303E05A-MO:
ERES2000
OEM3400E05A-MO:
ERES2000
OEM3401E10A-MO:
ERES2000
OEM2300E05A-MO:
ERES4000
OEM2303E10A-MO:
ERES4000
OEM3400E10A-MO:
ERES4000
OEM3401E10A-MO:
ERES4000
OEM2300E20A-MO:
ERES8000
OEM2303E20A-MO:
ERES8000
OEM3400E20A-MO:
ERES8000
OEM3401E20A-MO:
ERES8000
Encoder counts
missing.
1. Improper wiring.
2. Encoder slipping.
3. Encoder too hot.
4. Electrical noise.
5. Encoder frequency too high.
1. Check wiring.
2. Check and tighten encoder coupling.
3. Reduce encoder temperature with heatsink, thermal insulator, etc.
4.a. Shield wiring.
4.b. Use encoder with differential outputs.
5. Peak encoder frequency must be below 1.6MHz post-quadrature. Peak
frequency must account for velocity ripple.
Erratic operation.
1. Electrical noise and/or improper
shielding.
2. Improper wiring.
1.a. Reduce electrical noise or move OEM6250 away from noise source.
1.b. Refer to
Reducing Electrical Noise on page 28.
2. Check wiring for opens, shorts, & mis-wired connections.
LEDs
See
Diagnostic LEDs above (page 28)
Motion does not occur.
1. Check LEDs.
2. End-of-travel limits are active.
3. ENBL (enable) input not grounded.
4. Drive fault detected.
5. Improper wiring.
6. Load is jammed.
7. No torque from motor.
8. Max. allowable position error (
SMPER
value) exceeded.
1. See
Diagnostic LEDs above.
2.a. Hardware limit switches: Move load off of limits or disable limits with the
LH¯,¯
command.
2.b. Software limits: Set
LSPOS
to a value greater than
LSNEG
.
3. Ground the ENBL connection.
4.a. Check status with
TASXF
command (see bit #4).
4.b. Verify correct drive fault level setting (
DRFLVL
command value).
5. Check command (CMD), shutdown (SHTNC or SHTNO),
drive fault (DFT), and end-of-travel limit connections.
6. Remove power and clear jam.
7. See problem:
Torque, loss of.
8. Check status with
TASF
report (see bit #23), and issue the
DRIVE1
command to the affected axis.
Motion does not occur
in joystick mode.
1. Joystick Release input not grounded.
2. Improper wiring.
1. Ground Joystick Release input.
2. Check wiring for opens, shorts, and mis-wired connections.
