Technical clarity,
without the theatre.
Signal Field Guide is an independent reference for people who need to understand a signal before they can fix a machine.
BY DESIGN
The best troubleshooting step is often the one that makes the invisible measurable.
There is a particular kind of technical page that says a lot and helps very little. This site is designed to do the opposite: take one real field question, show the signal path, and make the next measurement obvious.
No stock photography is required for that job. The visual language here is built from original SVG diagrams, careful labels, and the numbers that matter at the terminals.
Read the field guide →Useful first.
Polished second.
One question per page
Each note starts with a narrow problem, not a keyword cloud. Related ideas are linked instead of padded into one giant article.
Diagrams earn their space
Every diagram should explain a path, a reference, a failure mode, or a decision. Decorative circuitry is not the point.
Sources stay visible
Manufacturer manuals and standards are starting points. The site adds interpretation, context, and clear boundaries around what is not universal.
Safety is not a footnote
Examples focus on low-voltage industrial I/O. Higher-risk work belongs with qualified people, site procedures, and the equipment documentation.
Built by engineers.
Tested in the plant.
Marcus Vance, PE — Lead Author & Technical Editor
Marcus is a licensed Professional Engineer (Electrical & Controls) with over 16 years of hands-on experience in PLC/DCS automation, SCADA integration, process instrumentation, and control panel engineering across heavy manufacturing and continuous-process plants.
Standards Compliance & Ground Truth
Every field circuit diagram, wire color assignment, and diagnostic sequence is cross-verified against official industry standards—including IEC 61131-2/9 (Programmable Controllers & IO-Link), IEC 60751 (Industrial Platinum RTD Resistance Elements), ISA-50.1 (Compatibility of Analog Signals for Process Control Systems), and TIA/EIA-485-A.
Continuous Review & Technical Corrections
Field hardware evolves and vendor quirks emerge. Our editorial inbox ([email protected]) is reviewed weekly. Whenever a manufacturer changes a terminal layout or an IEC revision updates a tolerance threshold, our notes and calculators are refreshed accordingly.
No mystery language.
If a term is necessary, it gets defined. If a diagram is simplified, it gets labelled. If a number depends on a manual, we say so.