Anweisungsliste

Anweisungsliste, often abbreviated AWL, is a PLC programming language used primarily with Siemens SIMATIC controllers. The term translates from German as “instruction list.” AWL is a textual, low‑level language that expresses control logic as a sequence of instructions and memory addresses, similar in spirit to an assembly language for PLCs.

Historically, AWL filled a role alongside other Siemens programming languages in Step7 and similar environments, especially for S5/S7 controllers. In the context of IEC 61131-3, AWL corresponds to the former Instruction List (IL). With the later IEC 61131-3 editions, IL was de-emphasized in favor of higher-level languages, and AWL became less prominent in new projects. Nevertheless, AWL remains part of many legacy systems and is still supported on older Siemens hardware, where it offers compact, text-based programmability.

Characteristics and structure: AWL programs consist of lines containing mnemonics and addresses, enabling operations on inputs, outputs, and internal memory. Programs are organized into blocks such as organization blocks (OB), function blocks (FB), and functions (FC). Typical elements include arithmetic, data handling, and logic operations performed on addresses representing inputs (I), outputs (Q), and memory areas (M, DB). AWL is appreciated for its precision and compactness, especially for complex algorithms or tightly optimized routines, but it is often considered harder to read and maintain than graphical languages like Ladder (LAD) or high-level languages like Structured Text (ST).

Current use: In modern automation, AWL is frequently replaced by ST or LAD for new projects due to readability and standardization advantages. However, it continues to be encountered in maintenance of older installations and in environments where legacy Siemens hardware remains in operation.