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.

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

2Parameter

3Delimiter

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.

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Sony RS-232C manual ACK 41H ‘A’, NAK 4EH ‘N’, Delimiter 0DH ‘CR’
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RS-232C specifications

The Sony RS-232C is a renowned communication standard that has been widely utilized in various electronic devices, enabling serial communication between computers and peripheral devices. This protocol is integral in various applications, including industrial automation, medical equipment, and consumer electronics.

One of the main features of the Sony RS-232C is its simplicity and ease of use. The standard utilizes a basic serial communication method, allowing for asynchronous data transmission. This means that data can be sent one bit at a time over a single channel, ensuring reliable communication over short distances, typically up to 50 feet, although longer distances can be achieved with proper cable management and signal boosters.

The technology behind the RS-232C standard employs voltage levels to represent binary data. Logic level zero is represented by a voltage between -3 to -25 volts, while logic level one is between +3 to +25 volts. This voltage differential is crucial for distinguishing between 'on' and 'off' states in electronic signaling. The standard supports data rates of up to 115.2 kbps, making it suitable for various applications, although it is generally limited in speed when compared to modern communication standards like USB or Ethernet.

In terms of characteristics, the Sony RS-232C supports both full-duplex and half-duplex communication, allowing for simultaneous transmission and reception of data, or one-directional data transfer, respectively. The protocol also includes control signals for flow control, such as RTS (Request to Send) and CTS (Clear to Send), which help manage data transmission and prevent data loss due to buffer overflow.

The RS-232C standard has 25-pin and 9-pin connector configurations, although many devices now utilize the more compact 9-pin DIN format. This legacy standard remains prevalent in industrial settings, as many devices still use RS-232 connections.

Despite the emergence of more advanced communication protocols, the reliability and robustness of the Sony RS-232C ensure that it remains an enduring choice for numerous applications. Its straightforward configuration, coupled with extensive documentation and support, makes it a favorable option for both new installations and the maintenance of legacy systems in various industries. As technology continues to evolve, the RS-232C standard remains a testament to the enduring principles of reliable communication.
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