Siemens M7-400 ユーザーズマニュアル

5-86

S7-400, M7-400 Programmable Controllers Module Specifications

A5E00069467-07

The following conditions apply when measuring the resistance and temperature
with the SM 431; AI 8 x 14 Bit:

Table 5-53 Channels for Resistance and Temperature Measurement with the SM 431; AI 8 

 

 14 Bit

Resistor 
(four-conductor terminal)

0, 2, 4 or 6

You must disable the

(

“Measuring Type” parameter for

channels n+1 (1, 3, 5, 7).

Resistor 
(three-conductor terminal)

0, 2, 4 or 6

( , , , )

The reason The connections of channel n+1 are used
to supply the resistance that is connected to
channel n

Thermal resistor
(linear, four-conductor termi-
nal)

0, 2, 4 or 6

channel n.

Thermal resistor
(linear, four-conductor termi-
nal)

0, 2, 4 or 6

If you select “RTD on Channel 0” as a reference junction for reference junction
compensation for thermocouples, the following applies:

Table 5-54 Thermocouple with Reference Junction Compensation via RTD on Channel 0

RTD on Channel 0

2 to 7

You must connect and parameterize on channel 0 a
resistance thermometer with linearization, a 3- or
4- conductor connection in the climatic range (channels
0 and 1 are thus assigned).

The reason: If channel 0 is to be used as the reference
junction, a resistance-type sensor must be connected
there to record absolute temperatures in the climatic
range.

Unused channels can usually be left open. Put the measuring range module in
position “A”. You can improve the noise immunity of the module in a measuring
environment with serious interference by short-circuiting the channels.

Disable the “Measuring Type” parameter for unused channels. In this way you
shorten the scan time of the module.