Terminal Connection Diagram And Block Diagram; Wiring Rules; Module View And Block Diagram Of The Sm 338; Pos-Input - Siemens SM 338 Reference Manual

1.1.1

Terminal Connection Diagram and Block Diagram

Fault indicator – red
SF
DI 0
DI 1
Figure 1-1

Module View and Block Diagram of the SM 338; POS-INPUT

Wiring rules

Please observe the following important rules of the wiring of the module:
• The ground of the encoder supply is connected non-isolated to the ground of
the CPU. Thus, connect pin 2 of the SM 338 (M) with low impedance with the
ground of the CPU.
• The encoder lines (pins 3 to 14) must be twisted pairs and shielded. Apply the
shield to both sides.
For the shield connection to the SM 338, use the shield connection element
(order number 6ES7390-5AA00-0AA0).
• If the output current (900 mA) of the encoder supply is exceeded, then you
must connect an external power supply.
Product Information on the Reference Manual Programmable Logic Controllers S7-300 Module Data Release 3
4
Voltage -
Short-circuit
monitoring
protection
Logic
24V
L+
1
M
2
3
4
RS 422
5
SSI
6
7
8
9
SSI
10
11
12
13
SSI
14
15
16
17
18
19
20
Twisted pair cables
Connection to the
ground of the CPU
OD (Data)
OD (Data)
OC (Clock)
OC (Clock)
1D (Data)
1D (Data)
1C (Clock)
1C (Clock)
2D (Data)
2D (Data)
2C (Clock)
2C (Clock)
DI 0 (Digital-
DI 1 input)
DC24V (encoder)
DC24V (encoder)
M (encoder)
M (encoder)
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