9.3.11
Connecting Resistance
Thermometers in the
Extended Pt 100 Range
The series-connected resistance thermometers (up to 8 Pt 100s) are fed
with a current of 2.5 mA (I
C+
/I
C-
) by a constant current generator. The
voltage at the Pt 100s is picked off at measurement inputs M+ and M-.
In this mode, the temperature range of approximately -100 °C to
+100 °C has a more accurate resolution. The mode is printed on the
cover of the module as follows:
"resistance thermometer compensated low range".
You should only use the 6ES5 498-1AA11 range card (
±
50 mV /
500 mV).
Unused inputs must be connected in parallel to a wired input. In the
following figure, for example, these are the inputs CH4 to CH7.
M+
M -
Ch 0
M+
M -
Ch 1
M+
M -
Ch 2
M+
M -
Ch 3
M+
M -
Ch 4
M+
M -
Ch 5
M+
M -
Ch 6
M+
M -
Ch 7
Ic -
Ic +
L +
L -
6ES5 498-
1AA11
6ES5 498-
1AA11
24V
M24V
2,5 mA
Figure 9-10
Connecting Resistance Thermometers in the Extended
Pt 100 Range
9
The 460 Analog Input Module
System Manual
C79000-B8576-C109-03
9 - 23
