Select a logic diagram builder by proving two requirements first: vendor neutrality and usable cross-reference handling. The available evidence identifies Siemens STEP 7 as the functional reference and LogiDOC as one candidate, but it does not establish supported platforms, file formats, PLC families, versions, licensing, or interoperability.
Define What “Neutral” Must Mean
“Neutral” is ambiguous until the engineering team defines it. It may mean documenting logic without binding the project to a PLC vendor, importing and exporting between engineering systems, or maintaining diagrams independently from executable PLC code. Treat these as separate requirements because the evidence does not confirm that any named product satisfies all three.
Use STEP 7 as a Workflow Benchmark
The stated requirement is a builder that handles cross-references and provides capabilities comparable to Siemens STEP 7. Convert that comparison into observable acceptance criteria instead of assuming feature equivalence.
| Requirement | Acceptance test | Evidence status |
|---|---|---|
| Cross-references | Create one symbol used in multiple diagram locations and confirm that the tool lists every use and opens each location. | Explicitly required |
| Vendor neutrality | Confirm whether diagrams remain usable without a vendor-specific PLC project or engineering package. | Required, but not defined |
| STEP 7-like workflow | List the exact STEP 7 functions the team depends on and test each function separately. | Requested without named functions beyond cross-references |
| Project exchange | Verify required import and export formats using a representative project. | Unknown |
| Executable output | Determine whether the deliverable is documentation only or logic intended for a PLC. | Unknown |
Evaluate LogiDOC and Other Candidates
LogiDOC is the only alternative product identified in the evidence, and it is described only as interesting. No supported feature, compatibility, or performance claim is available. Evaluate it and any additional candidate with the same controlled project.
- Define whether the required output is a neutral document, an exchange file, or executable PLC logic.
- Build a small representative diagram containing repeated symbol references.
- Generate the cross-reference results and verify that every use is present and navigable.
- Save, close, reopen, and revise the project to confirm that references remain intact.
- Test only the import, export, and vendor-independence requirements that the actual workflow needs.
- Record each result as pass, fail, or unverified; do not select a product on a general comparison with STEP 7.
Set a Defensible Selection Boundary
The evidence supports a requirements-led evaluation, not a product recommendation. A defensible decision requires the target diagram language, operating environment, deliverable format, collaboration needs, and relationship to executable PLC code. Until those items are specified and tested, LogiDOC remains a candidate rather than a confirmed replacement for any STEP 7 function.
FAQ
What should I test first in a neutral logic diagram builder?
Test cross-references by using one symbol in multiple locations, generating the reference list, and opening every reported use. Then confirm that the project remains usable without a vendor-specific PLC project.
Is LogiDOC a confirmed alternative to Siemens STEP 7?
No. The evidence identifies LogiDOC as a candidate but provides no verified compatibility, import/export, or feature-equivalence results.
Can a neutral diagram builder generate executable PLC logic?
The available evidence does not establish that capability. Decide whether the required deliverable is documentation, an exchange file, or executable logic, and verify that exact output before selection.