Compensation With Internal Reference Junction - Siemens SIMATIC ET 200AL System Manual

Thermocouples
5.3 Compensation for the reference junction temperature
5.3.2

Compensation with internal reference junction

Function principle
The reference junction for compensation via internal reference junction is at the terminals of
the analog input module. Wire the thermocouples or compensating lines directly to the
module inputs. The internal temperature sensor acquires the module temperature and
returns a compensating voltage.
Note that compensation via internal reference junction will not always reach the precision of
external compensation!
Procedure
Configuration steps:
1. Open the project in STEP 7.
2. In the device view, select the required analog module and the corresponding channel.
3. Select the "General" tab in the Inspector window of the selected module.
4. Select the "Inputs/Measuring" area.
5. Select the "Thermocouple" value as "Measurement type".
6. As "Reference junction", select the value "Internal reference junction".
Figure 5-2
84
Internal reference junction
Analog value processing
Function Manual, 06/2014, A5E03461439-AC