Circuit for resistance measurement
The following conditions apply when measuring the resistance and temperature with the SM
431; AI 8 x 14 Bit:
Table 5-56
Channels for resistance measurement of the SM 431; AI 8 x 14 Bit (6ES7431-1KF10-0AB0)
Measuring type parameter
Permissible for
channel n
Condition
Resistance
(4-conductor connection)
0, 2, 4 or 6
You must disable the "Measuring type" parameter for channels n+1
(1, 3, 5, 7).
Reason: The connections of channel n+1 are used to supply the
resistance that is connected to channel n.
Unused channels
Unused channels can be left open. Set the measuring range modules to position "B". You can
improve the noise immunity of the module in a measuring environment with serious
interference by interconnecting M- and M
ANA
.
Measuring ranges
Set the measuring ranges using the measuring range modules, and at the "measuring method"
parameter in
STEP 7.
Table 5-57
Measuring ranges of the SM 431; AI 8 x 14 Bit (6ES7431-1KF10-0AB0)
Selected measuring
method
Measuring range
(type of sensor)
Measuring range module set‐
tings
Description
V: Voltage
± 1 V
A
The digitized analog values are lis‐
ted in the section "Representation of
analog values for analog input chan‐
nels" in the voltage measuring
range.
1 to 5 V
± 10 V
B
2DMU: Current
(2-wire transducer)
4 to 20 mA
D
To supply these transducers with
current you must connect 24 V to the
L+ and M front connector terminals.
The digitized analog values are lis‐
ted in the section "Representation of
analog values for analog input chan‐
nels" in the current measuring range.
4DMU: Current
(4-wire transducer)
4 to 20 mA
± 20 mA
C
The digitized analog values are lis‐
ted in the section "Representation of
analog values for analog input chan‐
nels" in the current measuring range.
R-4L: Resistance
(4-conductor connection)
600 Ω
A
The digitized analog values are lis‐
ted in the section "Representation of
analog values for analog input chan‐
nels" in the resistance measuring
range.
Analog modules
5.21 Analog input module SM 431; AI 8 x 14 Bit (6ES7431-1KF20-0AB0)
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08
263