HMI
Human-Machine Interface
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
The operator-facing screen through which a person observes and commands an automated system. Its design is a GMP concern as well as an engineering one: what it displays, what it permits without a second check, and what it records are the practical boundary of operator error.
The human-machine interface is where an operator observes and commands an automated system, and its design carries GMP consequences as directly as the control logic behind it. What the screen shows, what it permits, and what it obscures determine the errors that are available to make — a confirmation step on an irreversible action, a parameter that cannot be changed while a batch is running, an alarm that cannot be silenced without an entry, are quality controls implemented in an interface.
It is also a boundary for the record. Values entered at the HMI become part of the batch record, so attribution, access control and audit trail apply at the point of entry, not merely in the historian behind it. The common weakness is a shared operator login at the terminal, which makes every subsequent record unattributable no matter how sound the downstream system is.
Alarm design deserves specific attention. An interface that produces more alarms than a person can act on trains operators to acknowledge without reading, which converts a safety and quality control into noise — and that is visible in the alarm history long before it is visible in an event.
- —Screen design determines which operator errors are available to make.
- —Entries at the HMI are batch-record entries — attribution and audit trail apply at the terminal.
- —Shared terminal logins make downstream records unattributable regardless of system design.
- —Confirmations, run-state locks and alarm entries are quality controls implemented in an interface.
- —Alarm flooding trains acknowledgement without reading; the alarm history shows it early.
EU GMP Annex 11 (§12 security, §14 electronic signature); ISPE GAMP 5 (2nd ed., 2022); IEC 62366-1 where the system is a medical device.
Frequently asked questions
What does HMI stand for?
HMI stands for Human-Machine Interface.
What is HMI?
The operator-facing screen through which a person observes and commands an automated system. Its design is a GMP concern as well as an engineering one: what it displays, what it permits without a second check, and what it records are the practical boundary of operator error.
Which regulations cover HMI?
EU GMP Annex 11 (§12 security, §14 electronic signature); ISPE GAMP 5 (2nd ed., 2022); IEC 62366-1 where the system is a medical device.