Appendix: Serial Programming Interface; Introduction; Command And Response Formats - Arcam DT91 Manuel

Appendix: Serial programming interface

Introduction

This section of the document describes the remote control protocol for controlling the DT91 via the
RS232 interface.
Conventions
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Data transfer format
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Command and response formats

Communication between the RC and the DT91 takes the form of sequences of bytes, with all commands
and responses having the same basic format. Communication between the two is full duplex. The DT91
shall always respond to a received command.
Each transmission by the RC shall be at least five bytes long in the following format:
<STR> <CC> <DL> <Data> <ETR>
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Each response by the DT91 shall be at least six bytes long in the following format:
<STR> <RC> <AC> <DL> <Data> <ETR>
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Note that the DT91 shall transmit messages whenever its status changes.
State changes as a result of other inputs
It is possible that the state of the DT91 may be changed as a result of user input via the front panel
buttons or via the IR remote control. Changes resulting from these inputs shall be relayed to the RC
(using the appropriate message type) as they occur.
For example, if the user changed the front panel display brightness using the
control, a display message (defined below) would be sent to the RC. A similar action would be taken for
all other state changes.
Answer codes
The following answer codes are defined:
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The remote controller is referred to as the 'RC'.
All values in this section are hexadecimal values, unless otherwise specified.
Transfer rate: 19,200bps.
1 start bit, 8 data bits, 1 stop bit, no parity, no flow control.
STR (Start transmission): 0x21
CC (Command code): the code for the command
DL (Data length): the number of data items following this item, excluding the ETR
Data: the parameters for the command
0xD
ETR (End transmission):
0x21
STR (Start transmission):
RC (Reply code): = command code
AC (Answer code): answer code (see below)
DL (Data length): the number of data items following this item, excluding the ETR
Data: the information associated with this response
ETR (End transmission): 0xD
0x1
Command OK :
Command Failed 0x0 :
The command has been accepted and processed completely.
The command has failed for some reason.
button on the remote
DISP
DT91
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