Tag Archives: PLC

PLC/HMI IOQ – What to Test?


Hello good people of the world! Today’s post is on initial control system Installation and Operational Qualification (IOQ)¬†of a simple system consisting of an Human/Machine Interface (HMI), Programmable Logic Controller (PLC), and any number of end devices (valves, pumps, sensors, etc.). The question is what should be tested?

Obviously there’s a ton of guidance out there (see e.g.: GAMP) that will have a lot more detail than this post. The purpose here is to list at a high level the tests that could be expected. So let’s get started!

Installation Qualification
IQ can be its own protocol or combined with OQ in an IOQ for cases without a ton of complexity. IQ is supposed to verify the installation of hardware, software, and any peripherals. You also want to check what documentation is available/applicable here. IQ tests may include:

  • Documentation Verification (e.g. SOPs, EREC/ESIG assessment, operating/maintenance manuals, panel and electrical drawings, etc.)
  • Hardware Verification: verify the make and model of major components at a minimum
  • Software Verification: verify/record software versions. You’ve got to know what you’ll be OQ’ing!
  • Configuration Verification: verify any hardware and/or software configuration. This could be two tests, one for hardware, one for software.
  • Loop Check Verification: verify loop checks are performed.
  • Alarm Configuration Verification: ideally alarms a setup in such a way that you don’t have to functionality test them all!
  • Any other critical installation items

Operational Qualification
OQ is the meat of your control qualification. Here you want to test critical functions, that hopefully you have identified earlier (see here for one approach). OQ may test:

  • Interlock Verification including e-stops. A lot of interlocks are safety/business related, but they’re often included in OQ due to how critical they are.
  • Functional Alarm Verification – be sure to include data loss/communication alarms
  • HMI Navigation and Layout Verification
  • Restart/Recovery Verification
  • Sequence of Operations Verification

What kinds of testing are you sure to cover in your control system IOQ protocols? Comment below.

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