What do the ALCMS server and database do?
The server turns screen commands into field commands and collects status back. The database remembers the configuration, the current state and the history.
The ALCMS server is the central computer of the control system. It takes commands from operator screens, sends them to CCRs and field controllers, collects status and alarms back, and applies the control logic and interlocks. The database holds the configuration (circuits, CCRs, zones, users and rights), the current state of each device and the history of events, alarms and operator actions.
Because the whole airfield is controlled through it, the central system is usually protected with a primary and standby server whose database is kept in step, separate backups, standby power, synchronised time and controlled access. If the server is lost, what the lights do depends on the design: field equipment often keeps its last state or runs under local control, so the failover and local-control procedures should be documented and tested.
Frequently Asked Questions
Q1What does the ALCMS server do?
It is the central computer. It receives commands from operator screens, sends them to the field controllers and CCRs, collects their status and alarms, applies the control logic and interlocks, and records events. Operators work through client screens, not on the server itself.
Q2What is stored in the ALCMS database?
Typically the system configuration (circuits, CCRs, zones, users and rights), the current state of each device, and the history of events, alarms and operator actions. The exact structure depends on the manufacturer.
Q3What happens to the lights if the server fails?
That depends on the design. Field controllers and CCRs usually keep their last state or can be run from local control, while the central screens lose status or control until a standby server takes over. The failure flow for your system should be documented and tested.
Q4Why use a primary and a standby server?
So one failure does not take away central control and monitoring. The standby follows the primary and its database is kept in step, so it can take over automatically or by operator action. Failover should be tested, not assumed.
Q5Why is backup needed if the database is already mirrored?
A mirrored copy repeats mistakes and corruption as well as good data. Separate, regular backups of configuration and logs allow recovery after a bad change, a failed disk or a cyber incident.
Q6Who should be able to change the configuration?
Only authorised, named users. Changes to circuits, interlocks or rights should be controlled and recorded in the audit trail, because they affect how the airfield lighting responds to commands.
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