Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Automation fundamentals, platforms and components

Assembler (programming)

Also known as: Assembly language

German: Assembler

In programming, assembler refers to a low-level language whose mnemonic instructions map almost one-to-one to a processor's machine code, and to the program that translates this language into machine code.

  • Automation components

In one sentence

Assembler is a low-level language whose mnemonic instructions map nearly one-to-one to machine code, and the tool that translates it.

Example

Firmware for a small sensor module contains an interrupt routine written in assembler to meet a tight timing requirement.

How it applies

  • Engineering: Assembler is used where direct hardware access or exact timing matters, such as boot code, interrupt handlers and very small microcontrollers. Most PLC and application code today is written in higher-level languages.
  • Maintenance: Assembler code is tied to one processor family, so hardware changes often require rewriting it. Legacy controllers may still contain such code.
  • Documentation: When a product contains assembler routines, the software documentation should state the target processor, the toolchain version and the purpose of each routine, because the code is hard to read without context.

Assembler vs. instruction list

Instruction list (IL) from IEC 61131-3 looks similar, with one operation and one Operand per line, but it is a PLC language that is compiled for the controller and is independent of the processor. IL was marked as deprecated in the third edition of IEC 61131-3. Assembler is processor-specific.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: AI TechDoc Knowledge editorial definition, based on general computer engineering practice

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Knowledge and are not part of any standard.

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