{"sections":[{"heading":"Check the exact restriction","paragraphs":["The maintained manual documents variable-step support for PHASE analysis with BDF integration. LOSSLESS transmission lines block this mode; an untyped T element defaults to LOSSLESS."]},{"heading":"Choose a valid run","steps":["Read the diagnostic's list of blocking lines and check the model assigned to each.","Use a validated fixed-step setup for LOSSLESS lines.","Use LCLADDER only when its finite LC-ladder approximation is physically appropriate. Do not change the model merely to silence the restriction.","Repeat the calculation with a smaller nominal step when validating edges or amplitudes; accepted settings alone do not establish convergence."]}],"canonical_url":"https://www.sun-magnetics.com/knowledge-base/josim-variable-step-lines","url":"/knowledge-base/josim-variable-step-lines","known_issues":[],"search_record":{"execution":false,"relatedProducts":[],"version_tags":["JoSIM-Pro 2.9 target"],"text":"Variable-step mode rejects a transmission line Use the documented analysis/integration combination and check whether the selected line model supports variable stepping. JoSIM-Pro 2.9.0 release target; review-build/source evidence Troubleshooting Check the exact restriction The maintained manual documents variable-step support for PHASE analysis with BDF integration. LOSSLESS transmission lines block this mode; an untyped T element defaults to LOSSLESS.  Choose a valid run Read the diagnostic's list of blocking lines and check the model assigned to each. Use a validated fixed-step setup for LOSSLESS lines. Use LCLADDER only when its finite LC-ladder approximation is physically appropriate. Do not change the model merely to silence the restriction. Repeat the calculation with a smaller nominal step when validating edges or amplitudes; accepted settings alone do not establish convergence. ","id":"josim-variable-step-lines","keywords":"","kind":"Troubleshooting","title":"Variable-step mode rejects a transmission line","product":"JoSIM-Pro"},"version":"2.9.0 release target; review-build/source evidence","id":"josim-variable-step-lines","related":["/knowledge-base/josim-transmission-models","/knowledge-base/josim-singular-circuit"],"downloads":[],"publication_status":"published","numerical_output":null,"provenance":{"execution_checks":[],"figure_evidence":[],"review_notes":["Support history informed this draft. Current-source guidance has been checked; a fresh walkthrough on the intended distributed release and product-owner review remain pending."],"scope":"Recorded inputs/builds only. Complete walkthrough and final-package acceptance remain separate.","verification_requirements":{"gui_method":"not-required-for-this-answer","status":"review-incomplete","illustrations":"not-required-for-this-answer","required":["technical-review","release-applicability","recovery"],"legacy_walkthrough_field":"pending retained; not evidence of a complete scenario"},"sources":[{"id":"support:SUP-016","section":"Generalised editorial finding; outcome qualification retained"},{"id":"josim-pro:docs/manual_source/sections/troubleshooting.tex","section":"Variable-step mode or runtime options are incompatible with the netlist"},{"id":"owner:technical-review-20261102","section":"JoSIM-Pro 2.9 chosen as the public starting path; release availability must be checked before publication"}]},"title":"Variable-step mode rejects a transmission line","type":"Troubleshooting","markdown_url":"/_functions/kbResource?path=markdown%2Fjosim-variable-step-lines.md","summary":"Use the documented analysis/integration combination and check whether the selected line model supports variable stepping.","product":"JoSIM-Pro"}