4-4 Troubleshooting
General Troubleshooting
The controller and keypad cannot be repaired in the field. If a unit fails, do not
disassemble it. Return it to the factory for replacement.
Problem
Possible Solution
Controller & keypad dead.
1. Check main fuse shown in Figs. 5 & 6.
2. Check power supply to controller.
Keypad dead, but controller
1. Check wiring between keypad and controller, Figure 12.
LED’s are on.
Keypad Fault LED “On”
1. Keypad microprocessor has malfunctioned. Turn the controller off and back on. If the
keypad Fault LED does not go off, return the keypad to the factory.
Menu operation Slow on
1. Check KEYBOARD QTY programming. If it is set for two keypads, but only one is
keypad display
connected, menu operation will be very slow.
COMM FAILURE—HOST TO
1. This message may flash briefly on power-up under normal conditions.
KEYBOARD message
2. If the message persists, check keypad wiring connections at keypad and controller,
Figure 12.
3. Check DIP switch settings, Figures 13 & 14.
4. Be sure Input Terminal #15, Figure 7, is not energized.
Programming functions not
1. Programming not enabled. See Figure 12, and also ENABLE CODES for details.
accessible.
POS (position) frozen at “0”
1. Encoder or encoder wiring may have failed. Unplug cable at encoder and plug a
spare encoder into the cable. If this solves the problem replace the encoder on the
machine. If not, prepare a short encoder cable (Fig. 16), unplug the cable at the
controller, and plug the short cable with spare encoder into the controller. If this solves
the problem, replace the cable on the machine. See page 4-3 for more.
POS (position) moves opposite 1. Check INCREASING DIR for the correct direction of rotation.
to machine direction.
2. Check encoder wiring, Figure 16.
POS (position) does not
1. Verify that OFFSET is correct. Once set, the offset value should not change. If it
match machine position.
does, check the encoder coupling to be sure it is not loose. Also see “Encoder Trouble-
shooting,” page 4-3. An intermittent encoder connection on controller pins 1, 2, 3, 5,
or 9 might cause POS to lag the actual encoder position until the next “zero” pulse
(“Z” signal) is received from the encoder.
Serial communications
1. Check COMMUNICATIONS programming to be sure type, baud rate, and address
not working
are correctly set.
2. Be sure the DIP switches for the PLuS-to-host communications are set correctly as
shown in Figure 13.
3. Check communication cable wiring, Figure 2-15.
Outputs cycling regularly at
1. Check that the correct program number is active.
incorrect machine positions
2. Check the setpoints of the output(s) in question. Also check SPEED COMP settings.
3. Verify that OFFSET is correct.
Erratic Operation
1. Run the Watchdog Timer test described under MEMORY TESTS in the programming
section of this manual.
2. See “Encoder Troubleshooting,” page 4-3.
(continued)
