Prepare a FAT package.
From engineering documents to a factory acceptance test (FAT) package ready for vendor witness
Preparing a factory acceptance test (FAT) package is the engineering process of assembling everything a vendor or integrator needs to demonstrate that a system (typically a PLC, a DCS, an MCC, or a packaged skid) meets its specification before it ships from the vendor facility. The FAT package carries the test plan keyed to the specification, the per-tag verification matrix, the loop check sheets for I/O loops, the simulation sequence for sequence-of-events verification, and the punch-list template. FAT discipline drives the field discovery: a deficiency caught at FAT is an order of magnitude cheaper than the same deficiency caught at site.
Inputs.
- +Specification (PLC functional spec, DCS HMI spec, SIS SRS, MCC schedule)
- +Project I/O list
- +Loop diagrams
- +Cause-and-effect matrix (for SIS)
- +Alarm rationalization (for DCS / SCADA)
Outputs.
- →Per-tag verification matrix (one row per I/O tag with expected / verified columns)
- →Per-loop check sheet template for I/O loops
- →Per-SIF action verification template (for SIS scope)
- →Per-bucket verification sheet (for MCC scope)
- →Punch-list template
- →Export targets: Excel workbook + PDF binder + JSON for the FAT-witness tool
| System | FAT scope focus | Per-tag verification |
|---|---|---|
| PLC | I/O point-to-point + logic | Every I/O tag mapped to physical I/O |
| DCS | I/O + HMI + alarm + sequence | Every alarm tag rationalized per ISA 18.2 |
| SIS logic solver | SIF execution + voting | Per-SIF demand-to-action timing |
| MCC | Bucket-by-bucket + breaker coordination | Every bucket tested for trip + closing |
| Package skid | Functional + interface | Every skid I/O point verified at boundary |
Step by step.
- 01
Establish the I/O baseline
Extract the project I/O list. Each tag becomes a row in the verification matrix. Tag-level traceability to the source P&ID page is preserved.
- 02
Map I/O tags to physical I/O
Tags map to PLC rack-slot-channel addresses (TIA Portal Field Tag List, Rockwell I/O Configuration). The verification matrix carries the physical mapping per row.
- 03
Build the loop check sheet templates
Per-loop check sheet populates with the loop topology (sensor → input → logic → output → final element). Witness fields blank for the FAT-witness to fill.
- 04
Build the SIF verification (SIS scope)
Cause-and-effect matrix populates the per-SIF action verification. Demand simulation walks each SIF from sensor demand to final-element response.
- 05
Build the alarm verification (DCS scope)
ISA 18.2 alarm rationalization populates the per-alarm verification. Priority distribution validation runs across the alarm set.
- 06
Ship the FAT package
Excel workbook + PDF binder + JSON. The vendor and the owner-engineer witness the FAT against the same package.
Common questions.
Does the FAT package cover MCC FAT at the builder facility?
Yes. MCC FAT is a distinct scope: bucket-by-bucket starter testing, breaker coordination verification, control-wiring continuity, overload verification. The MCC FAT scope filters from the MCC schedule extraction; each bucket populates one row in the verification sheet.
How does this differ from SAT preparation?
FAT happens at the vendor facility before shipment; SAT happens on site after installation. FAT focuses on functional verification (does the system do what the spec says?); SAT focuses on field verification (does the field installation match the FAT-verified system?). The document scope overlaps but the witness sequence differs.
Start a workspace.
Upload the source documents, run the workflow, ship the document in the column shape the next consumer expects.