Page 13
06-Mar-1997
VME4ST Backplane technical manual
Doc. VLT-MAN-ESO-17130-0992
4.1.5 A,B,Z (Encoder Signals)
Incremental encoder signals. Input to MAC4-STP. TTL-level differential signals. Signals are
routed from function connectors CH1-CH4 to MAC4. Signal names are abbreviated as
follows :
Signal name
Signal
A1+
Axis 1, Encoder signal A, Positive
A1-
Axis 1, Encoder signal A, Negative
B1+
Axis 1, Encoder signal B, Positive
B1-
Axis 1, Encoder signal B, Negative
Z1+
Axis 1, Encoder signal Z, Positive
Z1-
Axis 1, Encoder signal Z, Negative
MAC4
VME4ST
VME4ST P2 BACKPLANE
MOTOR
CONNECTOR
(ONE AXIS)
VME
BUS
A+
A-
B+
B-
Z+
Z-
A+
A-
B+
B-
Z+
Z-
GND
G
N
D
SIGNAL A
SIGNAL B
SIGNAL Z
Fig 4.1.5.1. Incremental encoder signal connection. Only one axis shown.
Important note :
For stepper motor applications, normally no encoder is used. In these cases note that it is
extremely important to terminate the encoder inputs externally, in particular the Z+ and Z-
inputs. If this is not done, there is a high probability that MAC4-STP firmware will get stuck
due to internal hardware structure (noise pickup on high impedance inputs). If no encoder
will be used, either of the two following actions MUST be taken :