Why it matters
It closes the loop between the person who can see the data and the people on the floor who can act. Without it a monitoring system is a logger with a nice interface.
Systems & architecture
Emergency command
Emergency command is the ability to trigger an action on a field device remotely - typically sounding its alarm - from a monitoring interface.
How it works
The interface issues a command, which is queued and delivered to the device, which acts and acknowledges. The acknowledgement matters: an unacknowledged command is an assumption.
Example
An operator seeing a developing gas reading triggers the on-site alarm before anyone in the area has noticed.
In Alfa HazardX
A dashboard operator can trigger a node's alarm remotely. The same acknowledgement discipline governs the adaptive scanner, which waits for the base motor to confirm a move before sampling.
Read further
Related terms
- Risk state machineA risk state machine models hazard status as a set of discrete states with defined transitions between them, so that events are generated by changes of state rather than by individual readings.
- Industrial IoTIndustrial IoT is the use of networked sensing devices in industrial environments to collect operational data and make it available for monitoring, analysis and control.
- Local alarmA local alarm is an audible or visual warning produced by the sensing device itself, without depending on a network, server or remote service.