Key facts
- Brand
- Siemens
- Model
- S7-300/400
- Industry
- Industrial
- Documents
- 11
- Languages
- ZH
- Last added
- 2026-10-12
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Siemens SIMATIC S7-300/400 STL Programming Reference Manual
This document serves as a reference manual for programming the SIMATIC S7-300 and S7-400 programmable controllers using the Statement List (STL) language. It details the syntax and functionality of STL elements, including logical operations, data handling, and program control instructions. The manual is part of the STEP 7 reference materials and is intended for programmers, operators, and maintenance personnel with general automation knowledge. This manual is written in Chinese.
Read onlineSiemens S7-300/400 specifications
| Supply Voltage (General) | AC220V, 50HZ |
|---|---|
| Isolation Voltage Limit (Eiso) | 75VDC or 60VAC |
| Power Reserve Margin | 0.5 to 1 times |
Source: Siemens S7-300/400 System Power Design and I/O Wiring Guide
All Siemens S7-300/400 documents by type
Day-to-day operation, settings and troubleshooting. Start here if the product is already set up.
Instruction set, parameters and examples for configuring or programming the device.
Questions answered in these manuals
What are the key factors for designing an S7-300/400 power system?
Design should consider reasonable grounding, anti-interference capability of the power system, and redundancy to prevent PLC power loss if external equipment fails.
From: Siemens S7-300/400 System Power Design and I/O Wiring Guide
How should analog signal grounds be connected for isolated input modules?
If the potential difference between Mana and M exceeds Eiso (75VDC or 60VAC), a connection must be established. Otherwise, they remain electrically disconnected.
From: Siemens S7-300/400 System Power Design and I/O Wiring Guide
How can I enable monitoring of S7‑SCL programs?
In the compiler options select “Create debug info” and also enable “Create object code” so that variables can be monitored.
Why does the compiler report “Character strings have different lengths”?
The warning occurs when source strings have mismatched lengths; declare the shorter string variable with a larger length (e.g., 254 characters) to eliminate the error.
What does the LED SF indicate?
The red SF LED lights when the CPU has a hardware fault or software error.
What does the RUN LED indicate?
The RUN LED (green) lights when the CPU is in RUN state.