The I/O list, read straight off the P&ID.
Fourteen columns, extracted from a P&ID package in whatever tag dialect it was drawn, signal class read from the drawing, exported into whichever PLC vendor format your team works in. The same row data, every downstream target.
The document that sizes the control system.
An I/O list is the register of every input and output signal the control system reads from or writes to the field. Each row is one signal, with its tag, service, control loop, and signal class. It is what sizes the PLC or DCS and drives marshalling, wiring, and checkout.
Tagsight builds it as the 14-column list below, read from the P&ID package and confirmed on the drawing canvas before it exports.
The fourteen columns.
Fourteen columns, tag through channel. The first come straight off the P&ID, range and units from an attached datasheet, and cabinet, slot, and channel are yours to assign downstream. Every row traces back to its source sheet.
| # | Column | What it carries |
|---|---|---|
| 01 | Tag | The identifier as it appears on the drawing, in its own dialect. |
| 02 | Service description | Process service the instrument measures or controls. |
| 03 | P&ID sheet | Source drawing number and revision. Traces every row back to its origin sheet. |
| 04 | Loop | Control-loop number for grouping and loop-folder organisation. |
| 05 | Signal class | AI, AO, DI, or DO, in the drawing's own dialect. You confirm the class on every row before export. |
| 06 | Sub-class | BPCS or SIS. Splits basic process control from safety per IEC 61511 separation. |
| 07 | Range | Engineering range when the drawing or attached datasheet shows it. |
| 08 | Units | Engineering units paired with the range, preserved exactly as on the drawing. |
| 09 | Set point | Process set point when specified. Blank otherwise. |
| 10 | Trip / alarm | Trip or alarm value for protective signals. Blank when not yet defined. |
| 11 | Cabinet | Marshalling cabinet ID. Owned by the controls engineer. |
| 12 | Card slot | PLC card slot assignment. Owned downstream during the I/O assignment pass. |
| 13 | Channel | Channel number within the card slot. Same downstream pass. |
| 14 | Notes / revisions | Revision marker, MOC reference, free-text note. |
Read in the dialect the drawing uses.
ISA 5.1, KKS and RDS-PP, IEC 81346, NORSOK, Dutch NEN, and in-house letter codes are each read in the form they were drawn in. The signal class is read from the convention the drawing itself uses and stays editable, so the list that reaches the controls team is one an engineer confirmed, not one a tool assumed.
- Signal class on every tag, AI / AO / DI / DO
- BPCS and SIS split for independent I/O
- Every row traceable to its source sheet
The same row data, in the file each tool imports.
Common questions
What is an I/O list?
What columns does an I/O list have?
What are the signal classes on an I/O list?
What is the difference between BPCS and SIS rows on an I/O list?
What formats can an I/O list export to?
Run it on your drawings.
Upload a P&ID set, get the schema above populated and classified, and export to the PLC vendor target your team uses.