Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · System coordination, integration and orchestration

Sequence synchronization

Also known as: Process synchronization

German: Ablaufsynchronisierung

In industrial automation, sequence synchronization is the alignment of two or more sequential control processes, such as step sequences in different machines or units, at defined synchronization points, so that one sequence does not proceed until the other has reached a required step.

  • System integration

In one sentence

Sequence synchronization aligns step sequences in different machines or units at defined points, so one waits until the other reaches a required step.

Example

The mixer sequence waits at its step "ready to discharge" until the receiving tank sequence reaches "ready to receive"; then both proceed with the transfer.

How it applies

  • Engineering: In IEC 61131-3 sequential function charts and ISA-88 phases, synchronization is done with transition conditions that check the other sequence's step or with explicit handshake signals. In batch control, ISA-88 describes phase-to-phase synchronization for transfers between units.
  • Commissioning: Test that sequences cannot pass each other at synchronization points and that an abort in one sequence brings the other into a defined state.
  • Operation: Diagnostics should show which sequence is waiting for which, since "waiting for partner" is a common reason for stopped processes.
  • Documentation: Show synchronization points in the functional specification with sequence diagrams or SFC excerpts, and describe in the operating instructions what operators can do when a sequence waits.

Sequence synchronization vs. state synchronization

Sequence synchronization coordinates the progress of processes at specific steps. State synchronization keeps copies of state data consistent between systems. The first is about control flow, the second about data.

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

Source: AI TechDoc Knowledge editorial definition, based on IEC 61131-3 SFC and ISA-88 batch control 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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