Siemens Simatic M7-400 Reference Manual page 347

Block Diagram of the SM 431; AI 8
M0+
M0+
R0 converter
M0–
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
Figure 5-41 Block Diagram of the SM 431; AI 8 x 16 Bit
Note
An external protective network is required in the signal leads in accordance with
IEC 61000-4-5 (150 V/14 mm MOV across each + and – input to chassis ground)
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
16 Bit
A/D
Internal
supply
Analog Modules
Backplane
Bus
bus
S7-400
interface
5-131