Blog.
Field notes on P&ID extraction, ISA 5.1, and instrumentation engineering.
Archive.
April 2026
- MOC and P&ID Documentation. Why I/O Lists DriftHow Management of Change breaks down when instrument documentation drifts from as-built. Why I/O lists go stale and how to catch it before commissioning.
- Loop Diagrams vs P&IDs. When to Use WhichThe practical difference between a P&ID and a loop diagram, what each document is authoritative for, and why mixing them up causes rework during commissioning.
- How to Read P&ID Instrument Symbols. Bubbles, Tags, LinesWhat the circles, lines, and letter codes on P&ID drawings mean. Covers ISA bubble types, tag number formats, signal line connections, and how to read them.
- Inside a TIA Portal Export. Siemens I/O TagsWalkthrough of the Siemens TIA Portal XML export structure for I/O tags. GlobalDB blocks, tag tables, S7-1500 versus S7-1200 differences, and what each export element actually contains.
- Scanned P&IDs vs CAD Exports. What to ExpectHow drawing source affects instrument extraction quality. Scanned brownfield P&IDs vs CAD-exported drawings. Resolution, readability, and getting clean results.
- I/O List Excel Template. Columns and FormatWhat columns belong in an instrument I/O list spreadsheet, how to structure it for loop checks, and the formatting mistakes that cause rework during commissioning.
- Cable Schedule Template for InstrumentationWhat belongs in an instrumentation cable schedule, how to structure it for E&I design and procurement, and how to build the first draft directly from a P&ID I/O list.
- Instrument Index vs I/O List vs Line List. What Each Document Is ForThe differences between an instrument index, an I/O list, and a line list, who consumes each document, and why mixing them causes problems during detailed engineering.
March 2026
- ISA 5.1 vs IEC 81346. Two Tag Identification Standards That Refuse to AgreeSide-by-side comparison of ISA 5.1 and IEC 81346 tag identification. Where they overlap, where they diverge, and how to handle projects that bridge both conventions.
- Estimating PLC I/O Count for a Project BidHow to count analog and digital I/O from engineering drawings without a full tag-by-tag walk, how to size card racks off the estimate, and the rules of thumb that hold up during detailed design.
- P&ID to PLCCreator. Export I/O Lists as Device IO CSVGenerate a PLCCreator-compatible Device IO List directly from P&ID drawings. Pick your PLC architecture, get a ready-to-import CSV with tag mapping.
- 4-20mA vs HART vs Fieldbus SignalsA working engineer's breakdown of 4-20mA, HART, Foundation Fieldbus, PROFIBUS PA, and PROFINET for instrument signals. Signal bandwidth, diagnostic capability, wiring cost, and selection criteria for new and brownfield projects.