Kenwood TS-870S Appendix D COM Connector Protocol, Hardware Description, Control Operation

APPENDICES ●

APPENDIX D: COM CONNECTOR

PROTOCOL

HARDWARE DESCRIPTION

The TS-870S uses a full-duplex, asynchronous, serial interface for communicating through the male 9-pin RS-232C COM connector. Bytes are constructed with 1 start bit, 8 data bits, and 1 stop bit (4800 bps can be configured for 1 or 2 stop bits). No parity is used. The pinout and the pin functions of the COM connector are as shown below:

COM CONNECTOR

9 8 7 6

5 4 3 2 1

TS-870S Rear panel view

COM	COM Pin Name			Function	I/O
Pin No.	(Ref.: Computer)			(Reference: TS-870S)
1			NC	Ñ	Ñ
2				Transmit data	Output
			RXD
3				Receive data	Input
		TXD
4			NC	Ñ	Ñ
5	GND			Signal ground
6			NC	Ñ	Ñ
7		RTS		Receive enable	Input
8		CTS		Transmit enable	Output
9			NC	Ñ	Ñ

RXD: The transmit data is the serial data transferred from the transceiver to the computer. The output uses negative logic.

TXD: The receive data is the serial data transferred from the computer to the transceiver. The input uses negative logic.

GND: This is the signal ground pin.

RTS: This signal is applied to the transceiver. It is used to inhibit transmit data from the transceiver when the computer is not ready to receive the data. The input uses positive logic. Inhibit is requested when the level is low.

CTS: This signal is applied from the transceiver. It is used to inhibit transmit data from the computer when the transceiver is not ready to receive the data. The output uses positive logic. Transmit data is stopped when the level is low.

CONTROL OPERATION

Most computers handle data in the form of ÒbitsÓ and ÒbytesÓ. A bit is the smallest piece of information that the computer can handle. A byte is composed of eight bits. This is the most convenient form for most computer data. This data may be sent in the form of either serial or parallel data strings. The parallel method is faster but more complicated, while the serial method is slower and requires less complicated equipment. The serial form is, therefore, a less expensive alternative.

Serial data transmission uses time-division methods over a single line. Using a single line also offers the advantage of reducing the number of errors due to line noise.

Only 3 lines are required theoretically for control of the transceiver via the computer:

¥Transmit data

¥Receive data

¥Ground

From a practical standpoint, it is also necessary to incorporate some means of controlling when this data transfer will occur. The computer and transceiver cannot be allowed to send data at the same time! The required control is achieved by using the RTS and CTS lines.

For example, the transceiver is placed into the transmit mode whenever the character string ÒTX;Ó is sent from the computer. The character string ÒTX;Ó is called a command. It tells the transceiver to do something. There are numerous commands available for control of the transceiver. These commands may be incorporated into a computer program written in any high level language. Programming methods vary from computer to computer; therefore, refer to the instruction manuals provided with the terminal program and computer.

COMMANDS

A command is composed of 2 alphabetical characters, various parameters, and the terminator to signal the end of the command.

EXAMPLE: Command to set VFO A to 7 MHz

FA 00007000000 ;

Terminator

Parameters

Command

COMMAND DESCRIPTION

A command may consist of either lower or upper case alphabetical characters.

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