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BEL DIGITAL AUDIO
Data count:
This is the total number of data bytes following, up to a maximum of 127.
Data:
The data required for the command is carried here. Each character can have a value of 0X00
to 0X7F i.e. 7 bits.
Checksum:
This is the modulo sum of the characters in the frame between the destination address and
the last data character inclusively. It is calculated thus:
DO
{
checksum = (character+checksum) AND 0x7F
}
FOR ALL CHARACTERS IN FRAME.
End Flag:
A character 0XFE ends the frame.
Commands
Commands from the remote controller to the BM-A1.
Code(Hex)
Function
General prompt for a reply
80
Use first data char as a second command
81
Request unit identifier
82
Set up switches Data count =5 See below for format
83
Set up alarm functions Data count=2 See below for format
84
Request Detail
85
Request Switches
86
Replies
Replies, when requested (e.g. 82), will consist of frames that contain the original command
value plus 0X40. So a request for an ident, 0x82, will elicit a reply of a frame containing 0xC2
and the ident string. (BM-A1Vn.n)
2004 BEL (Digital Audio) Ltd
BM-A1
16
BM-A1 serial protocol
Reply
C0 - ACK (OK)
C1 - NAK (send again)
ACK
C2.
ACK
ACK
C5
C6
Version 0.2
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