Siemens S5-135U/155U - Manual (Page 402)

9-20
System Manual
C79000-G8576-C199-06
9.3.10 Connecting Resistance Thermometers in the Standard 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 100’s is picked off at measurement inputs M+ and M-. In this mode, the
whole temperature range of the Pt 100 (-200
°
C to +840
°
C) is available. The
mode is printed on the cover of the module as follows:
“resistance thermometer uncompensated full range.” Other voltage sensors
can be connected in a floating circuit at the M+/M- inputs of a card which are
not assigned to resistance thermometers (voltage range 500 mV).
Pt 100
–
+
MUX
Card 1
460 Analog Input Module
#
D
A
CH0
CH2
CH1
CH3
M–
M +
Card 2
CH4
0...500 mV
U
CM
2)
1)
CH7
I
C–
L –
L +
0 V Bus
2.5 mA
const.
Pt 100
Pt 100
Pt 100
I
C+
U CM
0...500 mV
Range
Card for
4 Inputs
6ES5 498-
-1AA11
Range
Card for
4 Inputs
6ES5 498-
-1AA11
Figure 9-9 Connecting Resistance Thermometers in the Standard Pt 100 Range
1) If no Pt 100 is connected to CH4 to CH7, other voltages and currents can be measured at these channels with cards
6ES5 498-1AA21, 6ES5 498-1AA31, 6ES5 498-1AA41, 6ES5 498-1AA51, 6ES5 498-1AA61, 6ES5 498-1AA71.
2) When cards 6ES5 498-1AA41, 6ES5 498-1AA51 or 6ES5 498-1AA71 are used, a short-circuit jumper is not required.
Analog Input/Output Modules