553BTechnical specifications
A.7 Thermocouple and RTD signal modules (SMs)
S7-1200 Programmable controller
710
System Manual, 11/2011, A5E02486680-05
Table A- 94 Analog inputs
Model
SM 1231 AI 4 x 16 bit TC
SM 1231 AI 8 x 16 bit TC
Number of inputs
4
8
Range
Nominal range (data word)
Overrange/underrange (data word)
Overflow/underflow (data word)
See Thermocouple selection table
(Page 712).
See Thermocouple selection table
Temperature
0.1° C/0.1° F
0.1° C/0.1° F
Resolution
Voltage
15 bits plus sign
15 bits plus sign
Maximum withstand voltage
± 35 V
± 35 V
Noise rejection
85 dB for selected filter setting
(10 Hz, 50 Hz, 60 Hz or 400 Hz)
85 dB for selected filter setting
(10 Hz, 50 Hz, 60 Hz or 400 Hz)
Common mode rejection
> 120 dB at 120 VAC
> 120 dB at 120 VAC
Impedance
≥ 10 MΩ
≥ 10 MΩ
Field 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
120 VAC
120 VAC
Accuracy (25°C / 0 to 55°C)
See Thermocouple selection table
(Page 712).
See Thermocouple selection table
Repeatability
±0.05% FS
±0.05% FS
Measuring principle
Integrating
Integrating
Module update time
See Noise reduction selection table
(Page 712).
See Noise reduction selection table
Cold junction error
±1.5°C
±1.5°C
Cable length (meters)
100 meters to sensor max.
100 meters to sensor max.
Wire resistance
100 Ω max.
100 Ω max.
Table A- 95 Diagnostics
Model
SM 1231 AI 4 x 16 bit TC
SM 1231 AI 8 x 16 bit TC
Overflow/underflow
1
Yes
Yes
Wire break (current mode only)
2
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
When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.