Siemens Simatic S7-300 - Page 360

Analog Modules
4-154
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Terminal Connection Diagram and Block Diagram of the SM 331; AI 2 x 12 bits
Fault indicator – red
Thermocouples,
Voltage measurement
Current measurement
Resistance test
M
0 +
M
0
*
M
1 +
SF
Internal
supply
L+
Current
source
Multi-
plexer
Meas. range
module
None
ADC
Isolation
Backplane
bus
interface
SF
+
Internal
compensation
CH0
M
0 +
CH0
M
0
*
I
C0 +
CH1
M
1
*
I
C0
*
24V
Comp–/ Mana
Comp +
External
compensation
Comp
M
T
Figure 4-49 Module View and Block Diagram of the Analog Input Module SM 331; AI 2 x 12 bits
The input resistances depend on the measuring range selected (refer to the
technical specifications for the module).