I/O modules • 235
Incremental-encoder-interface 750-631
Modular I/O System
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Most quadrature encoders have an Index signal, or Z rev, as well as the incre-
mental signal. This signal provides one pulse per revolution with a duration
equal to an incremental pulse.
The inputs to the quadrature encoder module must be supplied from an en-
coder with Line Driver Outputs for proper operation. The 5 Volt DC output
may be used to power the encoder. The 24 Volt DC input supply must be pro-
vided from an external power supply.
The Gate and Latch inputs are 24 Volt DC.
Module Inputs and Outputs:
Input
Type
Function
Signal A and
Signal -A
Input, TTL
Incremental pulse signals for channel A
Signal B and
Signal -B
Input, TTL
Incremental pulse signals for channel B
Signal C and
Signal -C
Input, TTL
Index pulse signals
Shield
Input
Shield connection for encoder wiring
Sensor 0V
Output
Supply return for encoder supply
5V
Output
5 Volt DC supply for encoder
+24V
Input
24 Volt DC supply, field connection
0V
Input
Supply return, field connection
Gate
Input, 24V
24 Volt DC input for gate signal
Latch
Input, 24V
24 Volt DC input for Latch signal
The Input Gate stops the counter. Only 0 V or an open connection will initiali-
ze the counter.
24 V stops the counting process.
The input Latch controls the writing of the actual counter value into the Latch
register. This input is activated by the control bit EN_LATEXT ("1").
EN_LACT has to be deactivated ("0"). The first change from 0 V to 24 V at
the Latch input writes the actual counter value into the Latch register.
The control byte has the following bits:
Bit 7 Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
x
CFAST_M
x
x
CNT_SET
EN_LATEXT
EN_LATC
0
x
Operating
mode
x
x
Counter set
Release Latch
Release
Index Pulse
Please note Bit 7 is a reserved bit and must always be set to 0. It is responsible
for register communication which is not described in this chapter.
