Technical specifications
A.14 Analog signal boards (SBs)
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
1527
Table A- 235 Resistance
Normal range
accuracy
@ 25 °C
Normal range
accuracy
-20 °C to 60 °C
300 Ω n/a 0 (0 Ω) 27648 (300 Ω) 352.767 Ω ±0.05% ±0.1%
1
Resistance values above the over-range maximum value are reported as 32767.
Note
The module reports 32767 on any activated channel with no sensor connected. If open wire
detection is also enabled, the module flashe
s the appropriate red LEDs.
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- 236 Noise reduction and update times for the RTD modules
Rejection frequency
selection
4-/2-wire, 1-channel module
Update time (seconds)
3-wire, 1-channel module
Update time (seconds)
1
To maintain module resolution and accuracy when the 400 Hz filter is selected, the integration time is 10 ms. This selec-
tion also rejects 100 Hz and 200 Hz noise.
Note
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 availa
ble 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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