NDA-30115 Revision 1.0 Page 21
Property Management System - Communication Interface Message Descriptions
Release for
Maintenance Either system may request a temporary release of the data link for maintenance
purposes by transmitting a Data Link Release Request message to the other system.
The receiving system will perform any necessary processing and return the Data
Link Release Confirmation message as soon as possible.
During the NEAX maintenance, the PMS may continue to send Nop Test
messages, provided that EIA pin 6 (Data Set Ready) from the NEAX is in the “on”
condition. The NEAX will turn on the EIA pin 6 “on” and respond to Nop Test
messages when maintenance is comp leted.
While the data link is release on reque st of the PMS, the NEAX will continue to
attempt to read Nop Test messages from the PMS. The PMS may set EIA pin 20
(Data Terminal Ready) to the “off” condition to indicate that reading should not be
attempted.
When EIA pin 20 is in the “on” state and a Nop Test message is received from th e
PMS, the NEAX will assume that PMS maintenance has ended and that
communication can be resumed.
NEAX Operations During Loss of Communication
The NEAX will continue to support the basic telecommunications functions i f the
data link or PMS become unavailable. Upon detection of a data link failure, the
NEAX will automatically switch to th e “Link Failed Mode” to perform the
following tasks:
•Enable Check In and Check Out on the Attendant Console and Front Desk
Term ina l.
•Continue support of Message Waiting and/or Controlled Restriction if both
features are active in the NEAX.
Recovery from Loss of Communication
In the event of a PMS failure, it is assumed that Check In and Check Out must be
done manually and entered into the P MS system at a later time. The PMS shoul d
not resume transmission of the Nop Test message and attempt to reestablish
communication until the database has been brought up to date. This prevents the
transmission of incorrect data prematurely through the database recovery
procedure.
In cases where the PMS has remained operational during a data link failure, the
PMS will continue to attempt sending Nop Test messages. A Nop Test Answer
message (either Normal or Recover ) from the NEAX will indicate that
communication has been reestablished.
A Nop Test Normal Answer message indicates that the NEAX has had no status
change during the data link failure period and has automatically switched back to
the normal operating mode of an active data link.
A Nop Test Recover Answer message indicates that the NEAX has failed and t hat
status memory has been initialized for each room with the following:
•Room Status is Occupied (Checked In),
•Controlled Restriction Level is set to the preassigned restriction,
•Message Waiting Lamps are off,
•Wake Up times are cleared.