Sony RS-232C - Manual (Page 5)

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Communication Protocol
The communication protocol is described below.
• When the SRP-X700P has received a command from computer successfully, the SRP-X700P returns “ACK” (Acknowledge). When the
SRP-X700P fails to process the command due to reception error or others, it returns “NAK” (Not Acknowledge).
• When a computer has sent a command, the computer should wait “ACK” or “NAK” to be returned from the SRP-X700P. Upon receipt of
the return, a computer can send the next command.
• If a computer does not receive any return even after 1000 ms has elapsed since the transmission of a command, it means that the SRP-
X700P has not received the command normally. A computer should re-send the command again.
• A command transmission from a computer should be completed within 500 ms.
If transmission of a command cannot be completed within 500 ms, the command will not be processed and “NAK” will be returned.
• When a computer receives “NAK” during transmission of a command, a computer should stop sending the command immediately.
Handshake Code
ACK: 41[H] ( ‘A’ )
When the SRP-X700P has received and processed the command from an external computer successfully, it returns “ACK” notifying that the
command is executed. There are cases that other data are added to “ACK” and are returned together depending on the command.
Refer to Command Reference for details.
NAK: 4E[H] ( ‘N’ )
When the SRP-X700P fails to process the command supplied from an external computer, it returns “NAK” to a computer.
DELIMITER: 0D[H] ( ‘CR’ )
The SRP-X700P adds the delimiter code 0D [H] (equivalent to the carriage return of the ASCII code) to the last byte of all commands.
Communication Packet Format
Communication packet has the variable data length.
A communication packet consists of command, parameter and delimiter as shown below.
1. Command
A command consists of the four bytes.
2. Parameter
Length of a parameter changes depending on command.
Refer to Command Reference for details.
3. Delimiter
The SRP-X700P adds the delimiter code 0D [H] (equivalent to the carriage return of the ASCII code) to the last byte of all commands.
Example; When selecting C with LINE4 SELECT.
43[H] 53[H] 45[H] 4C[H] 33[H] 0D[H] (‘C S E L 3 CR’)
1 Command
2 Parameter
3 Delimiter