4-3 Troubleshooting
Encoder Troubleshooting
Encoder Type
The encoder used with the PS-6244 controller is an incremental quadrature encoder.
The encoder sends three signals to the controller: A, B, and Z, as shown below in
Figure 23.
Failure Symptoms
Most encoder failures or wiring problems will affect the POS (position) display. Some of
the possible symptoms are listed below:
Pins 1, 2, 3, 5, 9:
Failure Before Startup
Position display remains at zero.
Failure During Operation
The display will freeze on the position at the time of circuit break. If the circuit is re-
connected before power is turned off, the display will resume incrementing until the
zero pulse (Signal “Z”) is received, at which time the display will return to its pro-
grammed offset value.
Pin 7:
Failure Before Startup
Position display remains at zero.
Failure During Operation
Operation will appear to be unaffected. However, errors in count values may accu-
mulate, and on subsequent startup, the display will remain at zero.
Depending on the type and timing of encoder failure, the machine may continue
operating normally until it is turned off. On subsequent startup, the POS (posi-
tion) display may be “frozen” at zero.
Figure 23—Quadrature Encoder Signals & Controller Pin Connections
Signal
A
B
Z
Function
Increments position; relationship with "B"
indicates direction.
Increments position; relationship with "A"
indicates direction.
Resets position to "0" once per revolution.
Pulses
Pin
Connection
1
+ENC
2
VREF
3
A
4
–A
5
B
6
–B
7
Z
8
–Z
9
COM
10
Shield
10-Pin Weidmiller TB4
