Simon Collings - RS-232 Interfacing for Receiver Control

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Using RS-232 with Kenwood Radios

Interface Unit: IF-232C (converts 5V TTL to RS-232 polar)
Note: an interface kit may also be required for some models (eg Kenwood IF-10A for TS-711/811, IF-10B for TS-940S and IF-10C for TS-140/680, IC-10 for TS-440s/R-5000- Check the requirements for your model before attempting to use RS-232)

Standard Connections Used: TXD, RXD, CTS, RTS, GND

Flow Control: Hardware (RTS/CTS)

Type of RS-232 Command Set: ASCII text, , 2-character command, variable length data , semi-colon terminator

Data Parameters: 4800 bps (fixed), 1 start, 8 data + 2 stop bits (higher data rates are supported with latest models)

Overview of RS-232 Command Set

Since the RS-232 command set used by the Kenwood range of radios is ASCII text, it is possible to connect a character based terminal and control the radio directly from a keyboard and screen. You can also use a PC and simple terminal software such as MS-Windows Terminal.

Commands can be either upper or lower case (ie not case sensitive) and comprise a two-character command, a data field of variable length and a terminator (which is the semi-colon ';' character).

Example:

FA00007000000; ................................ Set VFO A to 7.0 MHz

The radios respond with data in the same format as that used to send commands.

Common Commands

I don't propose to list the entire range of RS-232 commands that are available for the Kenwood range of radios, but I will include a couple to give a flavour of the command interface. Further details of the commands are given in the relevant Kenwood manuals for your model. I have only included details of the R-5000 here..

Function

Command
Prefix

Format

Set Frequency

FA/FB

The frequency is written to either VFO A or VFO B
Frequency value is represented in Hz using 11 digits

Example: FA00007200000; tunes VFO A to
7.2MHz

Set Mode

1	=LSB	3	=CW	5	=AM	7	=CWN
2	=USB	4	=FM	6	=FSK

Note: modes supported by some models may vary

Example: MD1; selects LSB mode

Read Frequency

FA/FB

Response is FAnnnnnnnnnnn;
Where nnnnnnnnnnn is the current frequency in Hz
in 11 columns

Read Mode

Response is MDn;
Where n is the mode number 1-7

A useful command implemented by the Kenwood range of radios is AI which switches on status reporting every ~1.5s so that it is not necessary for software to continously poll the radio.

Function

Command
Prefix

Format

Auto Information

The function is switched on when the parameter is 1
and off when 0.

Example: AI1; switches on auto information

The data sent every ~1.5 seconds is of the following
format:

Parameter

Bytes

Format

Command Response

1-2

Display Frequency

3-13

Frequency in Hz, in 11 columns

Step Frequency

14-18

Frequency in Hz, in 5 columns

RIT Frequency

19-23

The first column is either "+" or "-" and the following 4 columns give the frequency in Hz.

Example: +5320 is +5.32 kHz

RIT on/off

0=off, 1=on

XIT on/off

0=off, 1=on

Memory bank

Single digit indicating bank number
Note: TS-940S only

Memory channel

27-28

Memory channel number represented as two digits

TX/RX

0=Receiver, 1=Transmit

Mode

1	=LSB	3	=CW	5	=AM	7	=CWN
2	=USB	4	=FM	6	=FSK

Note: modes supported by some models may vary

Example: MD1; selects LSB mode

Function

0	=VFOA	2	=Memory
1	=VFO B	3	=COM

Scan on/off

0=off, 1=on

Split on/off

0=off, 1=on

Tone on/off

0=off, 1=on

Tone Frequency

35-36

A value in two digits (01-37) corresponding to the tone frequency when M.CH is displayed
Note: Not all radios support this feature

Offset

0=simplex, 1=+ve, 2=-ve
Note: Not all radios support this feature

terminator

;