Introduces the analog input/output scale conversion of S7-300/400 PLC, including the analog input/output template, FC105/FC106 function block usage and example programs.
The document describes the concept of analog input/output range conversion for engineering quantities such as pressure, temperature, flow and level. Sensors provide standard voltage, current, temperature or resistance signals that the PLC reads via analog input modules, converts to integer values, and then scales to engineering units using function blocks.
It details the required Siemens S7‑300/400 analog modules (SM331, SM332, SM334/335 for the S7‑300 series and SM431, SM432 for the S7‑400 series) and shows how to locate and use the FC105 (SCALE) and FC106 (UNSCALE) converting blocks in STEP 7, including parameter definitions and example programs for both bipolar and unipolar signal types. This manual is written in Chinese.
| Analog input module SM331 range | 0‑27648 integer for 4‑20 mA input |
|---|---|
| FC105 scaling constants (bipolar) | K1 = -27648.0, K2 = +27648.0 |
| FC105 scaling constants (unipolar) | K1 = 0.0, K2 = +27648.0 |
The Siemens S7‑300/400 PLC uses the FC105 (SCALE) and FC106 (UNSCALE) converting blocks for analog range conversion.
They are located under Program elements → Libraries → Standard Library → TL‑S7 Converting Blocks.
S7‑300 uses SM331 (input), SM332 (output) and SM334/335 (combined); S7‑400 uses SM431 (input) and SM432 (output).