The SM 1231 thermocouple modules enable temperatures to be measured with high precision using established thermocouples. In addition, low level analog signals in the ±80 mV range can be recorded. The SM 1231 thermocouple modules can be used with the CPUs of the S7-1200 series.

Siemens Modules S7-1200 Product Specifications:

Article number	6ES7231-5QD32-0XB0	6ES7231-5QF32-0XB0
	S7-1200, analog Input SM 1231 TC, 4 AI	S7-1200, analog Input SM 1231 TC, 8 AI
General information
Product type designation	SM 1231, AI 4×16 bit TC	SM 1231, AI 8×16 bit TC
Supply voltage
Rated value (DC)	24 V	24 V
Input current
Current consumption, typ.	40 mA	40 mA
from backplane bus 5 V DC, typ.	80 mA	80 mA
Power loss
Power loss, typ.	1.5 W	1.5 W
Analog inputs
Number of analog inputs	4; Thermocouples	8; Thermocouples
permissible input voltage for voltage input (destruction limit), max.	±35 V	±35 V
Technical unit for temperature measurement adjustable	Degrees Celsius/degrees Fahrenheit	Degrees Celsius/degrees Fahrenheit
Input ranges
● Voltage	Yes	Yes
● Current	No	No
● Thermocouple	Yes; J, K, T, E, R, S, N, C, TXK/XK(L); voltage range: ±80 mV	Yes; J, K, T, E, R & S, B, N, C, TXK/XK(L); voltage range: ±80 mV
● Resistance thermometer	No	No
● Resistance	No	No
Input ranges (rated values), voltages
● -80 mV to +80 mV	Yes	Yes
— Input resistance (-80 mV to +80 mV)	≥1 MOhm	≥1 MOhm
Input ranges (rated values), thermocouples
● Type B	Yes	Yes
● Type C	Yes	Yes
● Type E	Yes	Yes
● Type J	Yes	Yes
● Type K	Yes	Yes
● Type N	Yes	Yes
● Type R	Yes	Yes
● Type S	Yes	Yes
● Type T	Yes	Yes
● Type TXK/TXK(L) to GOST	Yes	Yes
Thermocouple (TC)
Temperature compensation
— parameterizable	No	No
Analog value generation for the inputs
Measurement principle	integrating	integrating
Integration and conversion time/resolution per channel
● Resolution with overrange (bit including sign), max.	15 bit; + sign	15 bit; + sign
● Integration time, parameterizable	No	No
● Interference voltage suppression for interference frequency f1 in Hz	85 dB at 50 / 60 / 400 Hz	85 dB at 50 / 60 / 400 Hz
Smoothing of measured values
● parameterizable	Yes	Yes
Errors/accuracies
Temperature error (relative to input range), (+/-)	25 °C ±0.1%, to 55 °C ±0.2% total measurement range	25 °C ±0.1%, to 55 °C ±0.2% total measurement range
Repeat accuracy in steady state at 25 °C (relative to output range), (+/-)	0.5 %	0.5 %
Interference voltage suppression for f = n x (f1 +/- 1 %), f1 = interference frequency
● Common mode interference, min.	120 dB	120 dB
Interrupts/diagnostics/status information
Alarms	Yes	Yes
Diagnostics function	Yes; Can be read out	Yes; Can be read out
Alarms
● Diagnostic alarm	Yes	Yes
Diagnoses
● Monitoring the supply voltage	Yes	Yes
● Wire-break	Yes	Yes
Diagnostics indication LED
● for status of the inputs	Yes	Yes
● for maintenance	Yes	Yes
Degree and class of protection
IP degree of protection	IP20	IP20
Standards, approvals, certificates
CE mark	Yes	Yes
CSA approval	Yes	Yes
UL approval	Yes	Yes
cULus	Yes	Yes
FM approval	Yes	Yes
RCM (formerly C-TICK)	Yes	Yes
KC approval	Yes	Yes
Marine approval	Yes	Yes
Ambient conditions
Free fall
● Fall height, max.	0.3 m; five times, in product package	0.3 m; five times, in product package
Ambient temperature during operation
● min.	-20 °C	-20 °C
● max.	60 °C	60 °C
● horizontal installation, min.	-20 °C	-20 °C
● horizontal installation, max.	60 °C	60 °C
● vertical installation, min.	-20 °C	-20 °C
● vertical installation, max.	50 °C	50 °C
Ambient temperature during storage/transportation
● min.	-40 °C	-40 °C
● max.	70 °C	70 °C
Air pressure acc. to IEC 60068-2-13
● Operation, min.	795 hPa	795 hPa
● Operation, max.	1 080 hPa	1 080 hPa
● Storage/transport, min.	660 hPa	660 hPa
● Storage/transport, max.	1 080 hPa	1 080 hPa
Relative humidity
● Operation at 25 ℃ without condensation, max.	95 %	95 %
Pollutant concentrations
● SO2 at RH < 60% without condensation	S02: < 0.5 ppm; H2S: < 0.1 ppm; RH < 60% condensation-free	S02: < 0.5 ppm; H2S: < 0.1 ppm; RH < 60% condensation-free
connection method / header
required front connector	Yes	Yes
Mechanics/material
Enclosure material (front)
● Plastic	Yes	Yes
Dimensions
Width	45 mm	45 mm
Height	100 mm	100 mm
Depth	75 mm	75 mm
Weights
Weight, approx.	180 g	220 g