How can I change 2 Wires to 3 Wires Pt100 AI893
can someone please tell me how I can change 2wire Pt100 to 3wire Pt100 at the Card? And what kind of building block do I have to use?
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If I understood You correctly You are asking what's the difference between connecting 2- and 3-wire Pt100 to AI 893. If that's the case, then consult diagram below:
There is no diference in software configuration. You simply connect wires, assign variable and scale it.
Source: 3BSE020927R4001_S800_Modules and Termination Units with Intrinsic Safety Interface
You can either use SCAL block or, if You need additional linearization, SCAL + LIN blocks. The input range and output range must be set according to Your module settings. It's becouse in S800 modules analog process values are coded according to table below (the values has no over or underrange).
AI 893 has only these two ranges for Pt100, so if You use degrees Celcius the input range for SCAL block is -7529 to 32000 for temperatures (output range) -200 to 850*C. For degrees Fahrenheit use the other ones in the example above.
If You need some info on LIN block, check the file attached.