March 2003
M2303-00-P00-805
21
8
Responses from the Remote Radio
Commands sent to the remote AVL radio generally require a response. The Reset command is the only
exception to this. The response from the remote radio is sent as an SDM. It has the format :
[RESPONSE] [DATA]
The SDM is sent by the remote AVL radio over-air to the despatcher radio where it is then retrieved by the
AVL application using the GET_SDM CCDI command.
The [RESPONSE] byte is specific to the command that was sent. The [DATA] is either an AVL report or other
data determined by the response type.
[RESPONSE]
The [RESPONSE] is a one byte responses to the command from the AVL application.
The table below shows the structure of the [RESPONSE].
[RESPONSE]
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Function
1
Response Type
Radio Status / ACK Parameter
[RESPONSE] parts
Function
Byte 1 : Bits 0 - 3
Radio Status / ACK Parameters
These bits are set depending on the Response Type being sent. Refer to the table
below for the options.
Byte 1 : Bits 4 - 6
Response Type
000 :
AVL Report
- send the AVL report in response to the
Poll
command. The AVL report contains up to 17 8-bit bytes of data.
001 :
Read Database ACK
- sent in response to a
Read Database
command
010 :
Program Database ACK
- sent in response to a
Program
Database
command.
011 :
Control ACK
- sent in response to the
Control AUX
command
100 - 111 : reserved
Byte 1 : Bit 7
Always 1
