Rtd And Thermocouple Modules; Sb 1231 Rtd And Sb 1231 Tc Specifications - Siemens SIMATIC S7-1200 Manual

Technical specifications
A.7 RTD and Thermocouple modules
A.7

RTD and Thermocouple modules

The thermocouple (TC) modules (SB 1231 TC and SM 1231 TC) measure the value of
voltage connected to the analog inputs. This value can be either temperature from a TC or
volts.
● If voltage, the nominal range full scale value will be decimal 27648.
● If temperature, the value will be reported in degrees multiplied by ten (for example, 25.3
The RTD modules (SB 1231 RTD and SM 1231 RTD) measure the value of resistance
connected to the analog inputs. This value can be either temperature or resistance.
● If resistance, the nominal range full scale value will be decimal 27648.
● If temperature, the value will be reported in degrees multiplied by ten (for example, 25.3
The RTD modules support measurements with 2-wire, 3-wire and 4-wire connections to the
sensor resistor.
Note
The RTD and TC modules report 32767 on any activated channel with no sensor connected.
If open wire detection is also enabled, the module flashes the appropriate red LEDs.
When 500 Ω and 1000 Ω RTD ranges are used with other lower value resistors, the error
may increase to two times the specified error. Best accuracy will be achieved for the 10 Ω
RTD ranges if 4 wire connections are used.
The resistance of the connection wires in 2 wire mode will cause an error in the sensor
reading, and therefore accuracy is not guaranteed.
NOTICE
After power is applied, the module performs internal calibration for the analog-to-digital
converter. During this time the module reports a value of 32767 on each channel until valid
data is available on that channel. Your user program may need to allow for this initialization
time. Because the configuration of the module can vary the length of the initialization time,
you should verify the behavior of the module in your configuration. If required, you can
include logic in your user program to accommodate the initialization time of the module.
A.7.1

SB 1231 RTD and SB 1231 TC specifications

Note
To use these TC and RTD SBs, your CPU firmware must be V2.0 or higher.
262
degrees will be reported as decimal 253).
degrees will be reported as decimal 253).
Easy Book
Manual, 11/2011, A5E02486774-04