Identification should allow a technician to move from schematic to physical connection without guessing. Device tags, connection designations, wire numbers and terminal identifiers must each carry one defined meaning.

Learning objectives

Select an identification method, control uniqueness and preserve readable cross-references across panels and reports.

Core engineering principles

Device tags identify objects, not functions alone

One device can contain multiple contacts and coils. Contact references should point back to the owning object and connection point.

Wire numbers can follow potential or connection

Potential-based numbering groups electrically common nodes; point-to-point numbering identifies a physical wire. The project must choose and document the method.

Terminal identity includes strip and position

X1:15 and X2:15 are different interfaces. Level, disconnect and test functions should also be represented where multi-level terminals are used.

Duplicate numbers create hidden commissioning risk

Automated uniqueness checks are essential across repeated macros and copied pages.

Markers must survive the environment

Printed labels require legibility, adhesion, orientation and replacement data suitable for the LVC conditions.

Engineering application method

  1. Step 1: Define tag and numbering rules in the project standard.
  2. Step 2: Generate identifiers from the CAE model.
  3. Step 3: Check uniqueness and cross-references automatically.
  4. Step 4: Print and inspect physical markers.
  5. Step 5: Verify sample paths during FAT from schematic to terminal.

Practical example

Two terminals both marked 15 but on different strips can be clear in a drawing and ambiguous on site if the strip name is hidden. Full identifiers should appear where the connection is made.

Common mistakes

  • Using page numbers as permanent wire identity.
  • Reusing terminal numbers without strip prefix.
  • Typing cross-references manually.
  • Changing numbering after marker production.
  • Ignoring multi-level terminal positions.

Design and review checklist

  • Does each identifier have one meaning?
  • Are device contacts cross-referenced?
  • Are wires unique under the chosen method?
  • Can terminals be located physically?
  • Do labels match reports?

Standards basis and official sources

Engineering note: Verify the contracted standard edition, amendments, manufacturer evidence and project-specific studies before applying these principles to a supplied assembly.

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