Application Layer (AlphaCom Data Protocol)

Application Data

The application part of the information message has the general format: <br\>

<message class> <message data…….>

where:

<message class> UINT1

identifying class of message:

65 (0x41) ‘A’ = AlphaCom

66 (0x42) ‘B’ = SNMP­Like

67 (0x43) ‘C’ = TouchLine

68 (0x44) ‘D’ = Site specific (engineering use)

<message data> is a application level data in a format depending on <message class>.

The use of message class means that the AlphaNet protocol is prepared to transport and/or use messages with very different structure than the AlphaCom / Intercom related message formats used today.

Data Types

The following table identifies the data types used in the application data of the AlphaNet Data Protocol:

Data Type	Definition
UINT1	8 bits (one byte)
SINT1	1-­byte signed integer
UINT2	2­byte unsigned integer. MSB first
UINT4	4­byte unsigned integer. MSB first
BITMAP[1..n]	n­bits bitmap (multiple of 8). Always fills whole bytes. <br\>- Unused bits in last byte is set to 0. <br\>- First bit is the most significant (leftmost) bit in first byte.<br\>- Bits are numbered from 1, a byte contains bits 1..8.
VBITMAP[1..n]	Variable length bitmap with n bits. (n is a multiple of 8.) Structure:<br\>UINT1 - containing the number of bytes in the following bitmap. <br\>bitmap - always fills whole bytes. <br\>- Unused bits in last byte is set to 0. <br\>- First bit is the most significant (leftmost) bit in first byte.
TEXT16	16 characters (bytes) of text. Padded with spaces. <br\>ASCII values >= 32 (0x20) only.
CLOCK	Date & time structure:<br\>UINT2 Year (yyyy)<br\>UINT1 Month (mm)<br\>UINT1 Day (dd)<br\>UINT1 Hour (hh)<br\>UINT1 Minutes (mm)<br\>UINT1 Seconds (ss)
NET_OBJ_REF	AlphaCom Intercom Object Reference. <br\>Can both encode directory numbers and physical numbers

Network Object Reference (NET_OBJ_REF)

Further information: Network Object Reference

The NET_OBJ_REF is a “variant record” which has a header with byte count plus a type field.