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Page 14 NDA-30115 Revision 1.0
Architecture Property Management System - Communication Interface
The message format breaks down as follows:
• STX -- Start of text block. (One byte - 02H.)
• SA -- System Address. (One byte - ‘1’ [31H].)
• UA -- I/O Unit Address. (One byte - ‘!’ [21H].)
• EI -- Entry Index. (One byte - ‘L’ [4CH].)
• FTC -- Feature Code. (See below.) A list is provided in Appendix C, “Feature
Codes”.
• MSC -- Message Counter. This represents the length of the message. The count
of characters starts at the FTC field and ends at the last character of the body of
them message, not including the ETX. If the ETX character does not
immediately follow the character specified by the message counter, an invalid
message is assumed.
• FC -- Function Code. This specifies the individual operation and processing for
the feature designated by the Feature Code (FTC). A list is provided in
Appendix D, “Function Codes”.
• ETX -- End of text block. (One byte - 03H.)
Feature Codes range in value from 00 to FF (hex). These codes define the “Major
Category Codes” for service features.
Codes from 80 to FF are used as “Violation Codes”. When a specific message
received from the PMS cannot be processed for some reason, 80 (hex) is added to
the received Feature Code so that it will be handled as a Violation Code. If the
NEAX regards a text as a Violation Code, the system data of the NEAX may be
assigned so that a text of this type is returned to the PMS. Therefore, when the PMS
has received a Violation Code, provisions should be made for the PMS to print out
this violation.
A Violation Code message will be sent to the PMS in the following cases:
• When the message counter does not match the number of characters received.
• When a station number not existing in the NEAX is specified in the message
data from the PMS.
• Upon receipt of an invalid Wake Up time (e.g. 25:00).