Dynamic Reference Temperature With Module 8 Ai Rtd/Tc 8Xm12 - Siemens SIMATIC ET 200eco PN Operating Instructions Manual

I/O device analog input/analog output
10.1 I/O device analog input
10.1.7

Dynamic reference temperature with module 8 AI RTD/TC 8xM12

Properties
You can measure the reference junction temperature of the measuring point by using the
I/O device 8 AI RTD/TC 8xM12 or an external module from another station when you use the
compensation type "Dynamic reference temperature". To do so, the reference temperature is
transmitted with SFB 53 "WRREC" using the data record DS2 to the I/O device
8 AI RTD/TC 8xM12.
Requirements
● Standard function block SFB 53 "WRREC"
● User program
Programming
Observe the following notes on the user program:
● The permitted value range of the reference junction temperature in standard resolution
corresponds to the temperature range Pt100 Climatic for platinum RTDs.
● If a reference junction temperature is received in data record DS2 that is outside the
permitted value range, a diagnostic interrupt "Reference channel fault" is signaled if the
"Group diagnostics" parameter has been enabled.
● All inputs signal overflow (32767) when you start the I/O device 8 AI RTD/TC 8xM12.
After receiving a compensation value by means of the data record DS2, the I/O device
starts reading the TC inputs and signals correct data.
● The I/O device 8 AI RTD/TC 8xM12 has a watchdog set to 5 minutes that is reset after a
new compensation value was received by means of DS2. If the I/O device in standard
operation does not receive DS2 data within the 5-minute interval of the watchdog, a
diagnostic interrupt "Reference channel fault" is signaled if the "Group diagnostics"
parameter has been enabled.
● When you use ET 200eco PN modules or other modules for measuring the reference
junction temperature, the RTD module parameters/module parameters for the output
structure and measuring accuracy must be represented in the DS2 by bytes 0 and 1. The
figure below "Structure of data record DS2" illustrates this setting.
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Operating Instructions, 08/2016, A5E01250250-AJ
ET 200eco PN