Siemens SIMATIC S7 System Manual page 742

553BTechnical specifications
A.9 Analog signal boards (SBs)
Note
The module reports 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.
Table A- 147 Noise reduction and update times for the RTD modules
Rejection frequency
selection
400 Hz (2.5 ms)
60 Hz (16.6 ms)
50 Hz (20 ms)
10 Hz (100 ms)
To maintain module resolution and accuracy when the 400 Hz filter is selected, the integration time is 10 ms. This
1
selection also rejects 100 Hz and 200 Hz noise.
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 or the module in your configuration. If required, you can
include logic in your user program to accommodate the initialization time of the module.
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Integration time 4-/2-wire, 1-channel module
10 ms
1
16.67 ms
20 ms
100 ms
Update time (seconds)
0.036
0.056
0.066
0.306
3-wire, 1-channel module
Update time (seconds)
0.071
0.111
1.086
0.611
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05