Download Siemens Simatic S7-300 Technical data

Principles of analog value processing
4.6 Wiring and connecting thermocouples
Options of compensating for the reference junction temperature
Table 4- 1
Options of compensating for the reference junction temperature
Option
Explanations
No compensation
To record only the temperature difference between the measuring
point and reference junction.
Internal compensation
(for wiring and connecting, see Connecting
The internal compensation is based on a comparison using the
internal temperature (thermocouple internal comparison) of the
module.
External compensation with compensation box in
the feed lines of each thermocouple (the wiring and
connecting is shown in the diagram Wiring and
You have already measured and compensated for the reference
junction temperature (thermocouple external comparison) using an
interconnected compensating box in the feed lines of each
thermocouple.
thermocouples with internal compensation box to
electrically isolated analog inputs)
connecting of thermocouples with compensation
box to electrically isolated analog inputs and Wiring
and connecting of thermocouples with reference
junction (order no. M72166-xxx00) to electrically
isolated analog inputs)
Further signal processing is not required at the module.
Only for SM 331; AI 8 x TC:
You can measure the reference temperature using a (platinum or
External compensation with resistance thermometer nickel) resistance thermometer, and compute it in the module for any
thermocouple.
for recording the reference junction temperature
See also
Wiring and connecting thermocouples with internal compensation (Page 262)
Wiring and connecting thermocouples with external compensation (Page 263)
Wiring and connecting transducers to analog inputs (Page 248)
S7-300 Module data
Manual, 02/2013, A5E00105505-08
261