Siemens SIMATIC S7-1500 Manual page 31

Reference junction
The following settings can be configured for the reference junction parameter:
Table 4- 3 Possible parameter assignments for the reference junction parameter TC
Setting
Fixed reference temperature
Dynamic reference temperature
Internal reference junction
Hardware interrupt 1 or 2
Enabling of a hardware interrupt at violation of high limit 1 or 2 or low limit 1 or 2.
Low limit 1 or 2
Specifies the low limit threshold that triggers hardware interrupt 1 or 2.
High limit 1 or 2
Specifies the high limit threshold that triggers hardware interrupt 1 or 2.
Analog Input Module AI 4xU/I/RTD/TC ST (6ES7531-7QD00-0AB0)
Manual, 09/2016, A5E32366209-AC
Description
The reference junction temperature is configured and stored in the module as
a fixed value.
The reference junction temperature is transferred in the user program from the
CPU to the module by data records 192 to 195 using the WRREC (SFB 53)
instruction.
The reference junction temperature is determined using an integrated sensor
of the module.
Parameters/address space
4.3 Declaration of parameters
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