Siemens Simatic S7-400 - Manual (Page 339)

Analog Modules
5-123
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Block Diagram of the SM 431; AI 8 RTD 16 Bit
Backplane
bus
interface
Bus
S7-400
SO+0
SE+0
SE–0
AGND
SO+7
SE+7
SE–7
AGND
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
A/D
converter
Isolation
Internal
voltage
supply
Figure 5-38 Block Diagram of the SM 431; AI 8 x RTD 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)