The PMS can detect a system failure situation when no response is received from the system following the PMS to System ENQ retry sequences described here. Once this failure has been detected, the PMS should periodically send ENQ messages to the system. While the system is down, these messages will time out indicating that the system is still not available. When the system comes up from a reboot, it does not send any messages until it receives an ENQ from the PMS. The system queues its own transactions while waiting for the PMS to send an ENQ.
Once the system receives its first ENQ message from the PMS, the system will initiate the RTI sequence which begins with an ENQ to the PMS followed by the RTI message. If no RTI sequence is received by the PMS, the PMS can resume normal operation.
At this point, the PMS can either:
Honor the RTI by sending a General Reset (GRS) message to the system
NOT honor the RTI and simply send any applicable messages to the system
Honoring the RTI involves invoking the complete GRS cycle. The GRS cycle ensures that the system database reflects the PMS database.
Following the RTI message, the system will set a 2 minute timeout waiting for a GRS cycle to begin. The PMS may decide not to honor the RTI by simply resuming normal operation. During this two minute period the system will not initiate any messages (ie. Maid Status, Message Waiting, Alert, Message Registration) to the PMS and instead these will be queued for later delivery If no GRS message is received within the two minute period, the system will begin sending its own messages, including those queued up during the two minute period.
When the PMS is down, the system is able to track trunk calls, using SMDR, as well as using the Hotel/Motel feature package.
Prior to 3300 R8.0 and in the SX2000, the changing of Maid Status (Room Status Condition) must be monitored using the system operator console and the Hotel/Motel feature package. The system keeps a transaction buffer with the ability to store a maximum of 100 transactions. A transaction may either be for Message Registration or Maid Status (Room Status Condition). In the system database, information on Room Status Condition and on Message Registration is also maintained.
In 3300 R8.0 and above, a buffer exists for every room in the system and an up-to-date status of the room is maintained including Maid Status, Message Waiting Indicator, Credit Limit alert, and accumulated meter pulses.
While the PMS is down, the system will create a hotel log indicating the PMS is down
The system determines that the PMS is down when no transaction acknowledgment is received for a system initiated message within the 1 minute timeout period (20 tries every 3 seconds). It continues to send an ENQ every three seconds until the PMS recovers, and sends an ACK.
When the PMS system returns to service, the system creates a hotel log indicating the PMS has returned to service. All buffered messages are sent to the PMS via normal protocol.
If there is a fault with the PMS link, the PMS/system interface software sends a message to the maintenance software. The maintenance software responds by making entries in the Maintenance Log and raising an appropriate alarm.
