Siemens SITRANS T Series - How TF320 Works

4.4.6 How TF320 works
The functional principle is described below based on the function chart.
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① LED ⑥ HART modem
② Local display ⑦ Computer
③ Test terminals ⑧ Galvanic isolation
④ Feed splitter, e.g. SITRANS I100 ⑨ Input
⑤ Load A/D Analog-to-digital converter
μC1 Microcontroller, on the secondary side
Figure 4-22 Function chart for SITRANS TF with SITRANS TH320
• Input ⑨ for connecting di󹪜erent signal sources. Section: Input (Page 201).
• This signal is converted to a digital signal in an analog-to-digital converter (A/D).
• The digital signal is evaluated in a microcontroller (μC1) on the secondary side and corrected
to match the input characteristic.
• The digital signal is transferred via the galvanic isolation ⑧ to the microcontroller (μC2) on
the primary side.
• The analog output value is calculated in the microcontroller (μC1) on the primary side. The
functional status is indicated by LED ① and the communications data is prepared.
• The digital-to-analog converter (D/A) subsequently converts the signal into the output
current of 4 to 20 mA.
• The power supply source is located in the output signal circuit.
Description
4.4 SITRANS TF320/TF420
SITRANS TH100/TH320/TH420/TR320/TR420/TF320/TF420 with 4 to 20 mA/HART
56 Operating Instructions, 05/2020, A5E41864807-AB