Siemens S7-1200 System Manual page 926

Technical specifications
A.9 Thermocouple and RTD signal modules (SMs)
Technical data
Cable length (meters)
Wire resistance
Table A- 174 Diagnostics
Technical data
Overflow/underflow
1,2
Wire break
3
24 VDC low voltage
1
The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
1
the alarms are disabled in the module configuration.
For resistance ranges underflow detection is never enabled.
2
When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
3
random values.
The SM 1231 RTD analog signal module measures the value of resistance connected to the
module inputs. The measurement type can be selected as either "Resistor" or "Thermal
resistor".
● "Resistor": The nominal range full scale value will be decimal 27648.
● "Thermal resistor": The value will be reported in degrees multiplied by ten (for example,
25.3 degrees will be reported as decimal 253). The climatic range values will be reported
in degrees multiplied by one hundred (for example, 25.34 degrees will be reported as
decimal 2534).
The SM 1231 RTD module supports measurements with 2-wire, 3-wire and 4-wire
connections to the sensor resistor.
926
SM 1231 AI 4 x RTD x 16 bit
100 meters to sensor max.
20 Ω, 2.7 Ω for 10 Ω RTD max.
SM 1231 AI 4 x RTD x 16 bit
Yes
Yes
Yes
SM 1231 AI 8 x RTD x16 bit
100 meters to sensor max.
20 Ω, 2.7 Ω for 10 Ω RTD max.
SM 1231 AI 8 x RTD x16 bit
Yes
Yes
Yes
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG