Five checks to make before you hand an FDS to a programmer

A good handover saves days. A poor one costs weeks. Most of the delay in a PLC project does not come from hard engineering. It comes from questions that were always going to be asked and that nobody answered before the work started. A few quick checks on the FDS catch most of them. These are the five worth making first.

Check one: every I/O point has a tag name, a type and a description. A programmer cannot guess whether a signal is digital or analog, or whether an analog signal is a 4 to 20 mA loop or a 0 to 10 V one. If the name is missing they will invent one, and the invented name is the one that ends up on the HMI and in the alarm list.

Check two: every device has a defined state for power up and for a fault. Most specs describe what a valve or drive does during normal running. Far fewer say where it should be after a power loss or when its feedback goes bad. Does the valve fail open or closed? Does the drive restart on its own or wait for an operator? Leaving this blank means the programmer decides, and the process engineer finds out at commissioning.

Check three: every interlock names both the condition and the action. "Pump protected against dry running" is an intention. "Stop pump P101 when suction level LSL101 is low for more than five seconds" is something that can be programmed and tested. If a line in the FDS cannot be turned into a test, it is not finished.

Check four: every alarm says who sees it and what they should do. An alarm needs a priority, a message an operator can read at 3am and a first action. A list of alarms with no priorities usually becomes a list that nobody trusts.

Check five: anything marked TBC has an owner and a date. TBC is fine in a draft. It becomes a problem when it survives into the handover with nobody's name next to it. Each one is a decision that will be made by default, usually by whoever reaches it first and is least able to ask.

None of these checks need special tools. They need an hour with the document and someone willing to read it as if they had to build from it. The same checks apply whether the FDS was written by hand or generated. What changes is how early the gaps show up. A structured record gives every detail a place, so a missing state or a blank owner is easy to see, where a long Word file can hide it until someone goes looking.

FDSIQ is built around that idea. You can see how it works on How It Works.

An engineer reviews and tests everything FDSIQ and ScaffIQ generate before it goes anywhere near a running system.