Siemens Simatic S7-400 - Manual (Page 334)

Analog Modules
5-118
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Example
If you have select “current (two-wire transmitter)” for channel 6, you can only
disable the measuring method or set “current (two-wire transmitter)” for channel 7.
Circuit for Resistance and Temperature Measurement
The following conditions apply when measuring the resistance and temperature
with the SM 431; AI 16 x 16 Bit:
Table 5-67 Channels for Resistance and Temperature Measurement of the SM 431; AI 16 16 Bit
Measuring Type Parameter Permissible
for Channel n
Condition
Resistor
(four-conductor terminal) 0, 2, 4, 6, 8, 10,
12 or 14 You must disable the ( “Measuring Type” parameter
for channels n+1 (1, 3, 5, 7, 9, 11, 13, 15).
Resistor
three-conductor terminal 0, 2, 4, 6, 8, 10,
12 or 14
( , , , , , , , )
The reason The connections of channel n+1 are used
to supply the resistance that is connected to channel
Thermal resistor
(linear, four-conductor termi-
nal) 0, 2, 4, 6, 8, 10,
12 or 14
pp y
n.
Thermal resistor
(linear, four-conductor termi-
nal) 0, 2, 4, 6, 8, 10,
12 or 14
Thermocouple (linear) 0 to 15 You can select the reference junction. It is only
advisable to specify a reference junction with
thermocouples.
Circuit for Reference Junction Compensation for Thermocouples
If you select “RTD on Channel 0” as a reference junction for reference junction
compensation for thermocouples, the following applies:
Table 5-68 Reference Junction Compensation via RTD on Channel 0 of the SM 431; AI 16 16 Bit
Reference Junction
Parameter
Permissible
for
Channel n
Condition
RTD on Channel 0 2 to 15 You must connect and parameterize on channel 0 a
resistance thermometer with linearization, a 3- or
4- conductor terminal in climatic range. This means that
channels 0 and 1 are assigned.
The reason If channel 0 is to be used as the reference
junction, a resistance-type sensor must be connected
there to establish the absolute temperatures in the
climatic range.