Siemens SIMATIC User Manual

Analog modules
6.6 Analog input module SM 331; AI 8 x 13 Bit; (6ES7331-1KF02-0AB0)
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
343
Wiring: Resistance measurement with 2-, 3- and 4-wire connection
The following connection possibilities also apply to silicon temperature sensors and PTCs.
①
2-wire connection. Insert a bridge between M and S (no line resistance compensation).
②
3-wire connection
③
4-wire connection. The fourth line may not be wired (remains unused)
④
4-wire connection. The fourth line is routed to the terminal strip in the cabinet but is not wired.
⑤
Internal supply
⑥
+ 5 V from backplane bus
⑦
Logic and backplane bus interface
⑧
Electrical isolation
⑨
Multiplexer
⑩
Analog to Digital Converter (ADC)
⑪
Current source
Figure 6-12 Block diagram and terminal diagram
Note
It is not
necessary to interconnect the M- terminals when measuring using resistors,
resistance thermometers, PTCs, or silicon temperature sensors. However, interconnection of
the M
- terminals may enhance interference immunity.

Siemens SIMATIC Specifications

General

Product type designation	SIMATIC
CPU	Varies by model
Memory	Varies by model
Input/Output	Varies by model
Communication	Varies by model
Programming Language	STEP 7
Operating Temperature	0°C to 60°C (varies by model)
Protection Class	IP20
Category	Programmable Logic Controller (PLC)