553BTechnical specifications
A.7 Thermocouple and RTD signal modules (SMs)
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
715
Technical data
SM 1231 AI 4 x RTD x 16 bit
SM 1231 AI 8 x RTD x16 bit
Range
Nominal range (data word)
Overshoot/undershoot range
(data word)
Overflow/underflow (data word)
See RTD Sensor selection table
(Page 717).
See RTD Sensor selection table
Temperature
0.1° C/0.1° F
0.1° C/0.1° F
Resolution
Resistance
15 bits plus sign
15 bits plus sign
Maximum withstand voltage
± 35 V
± 35 V
Noise rejection
85 dB for the selected noise reduction
(10 Hz, 50 Hz, 60 Hz or 400 Hz)
85 dB for the selected noise reduction
(10 Hz, 50 Hz, 60 Hz or 400 Hz)
Common mode rejection
> 120dB
> 120dB
Impedance
≥ 10 MΩ
≥ 10 MΩ
Field side to logic
500 VAC
500 VAC
Field to 24 VDC
500 VAC
500 VAC
Isolation
24 VDC to logic
500 VAC
500 VAC
Channel to channel isolation
none
none
Accuracy
See RTD Sensor selection table
(Page 717).
See RTD Sensor selection table
Repeatability
±0.05% FS
±0.05% FS
Maximum sensor dissipation
0.5m W
0.5m W
Measuring principle
Integrating
Integrating
Module update time
See Noise reduction selection table
(Page 717).
See Noise reduction selection table
Cable length (meters)
100 meters to sensor max.
100 meters to sensor max.
Wire resistance
20 Ω, 2.7 Ω for 10 Ω RTD max.
20 Ω, 2.7 Ω for 10 Ω RTD max.
Table A- 102 Diagnostics
Technical data
SM 1231 AI 4 x RTD x 16 bit
SM 1231 AI 8 x RTD x16 bit
Overflow/underflow
1,2
Yes
Yes
Wire break
3
Yes
Yes
24 VDC low voltage
1
Yes
Yes
1
The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
the alarms are disabled in the module configuration.
2
For resistance ranges underflow detection is never enabled.
3
When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.