Siemens SIMATIC S5 Equipment Manual page 102

R 02/92
7.3.5 Instructions for Encoder Connections
The encoders are connected to the 50–way sub D connector of the basic module via a cable with
twisted pair conductors, according to RS 422/RS 485 specifications. The encoders can be either
connected to the input interface "optocoupler"( i.e., a current loop with approx. 7 mA, or to the
input interface "receiver" (set switch S2 accordingly)),
– In case of operation via the optocoupler:
The encoder is supplied via the encoder matching module.With the jumpers A– B
and C–D on the basic module, and the grounding connection with the program-
mable controller, only non-floating operation is possible.
For floating operation, a separate encoder supply is required, galvanically iso-
lated (i.e., without connection to the S5).
– In case of operation via the receiver:
The value of the terminating resistor R2 can be adapted to the wave resistance Zo
(see the data sheet of the respective encoder manufacturer) of the cable used.
Floating operation is not possible.
Zo = R2 see RS 485 specifications. The factory setting for Zo = R2 =100 S2
Maximum cable lengths:
The maximum cable length depends on the transfer frequency.
Encoder resolution g 10 bits -t transfer frequency=100 kHz ~ max. cable length 300 m
Encoder resolution >10 bits ~ transfer frequency = 200 kHz -+ max. cable length 150 m
Circuiting of the sense outputs
with sense
outputs
A circuiting of the sense outputs with a suitable encoder is required here or the
sense(+) and sense(–) outputs must be left open. Do not connect sense(+) and
sense 1 to ground or the encoder power supply since these voltages can other-
wise increase (up to 18 V).
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Encoder with sen-
se inputs
SENSE +
SENSE –
SENSE –
LOOP IN
LOOP OUT
etc.
Matching Module 4 for Absolute Encoders
7 – 11