Cat Data Protocol; Constructing And Sending Cat Commands - Yaesu FT-818ND Operating Manual

Hf/vhf/uhf ssb/cw/am/fm ultra-compact transceiver

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Table Of Contents

Table of Contents

All commands sent from the computer to the transceiver consist of five-byte blocks, with

up to 200 ms between each byte. The last byte in each block is the instruction opcode,

while the first four bytes of each block are arguments (either parameters for that instruc-

tion, or dummy values required to pad the block out to five bytes). Each byte consists of 1

start bit,8 data bits, no parity bit, and two stop bits.

Start

Bit

CAT DATA BYTE FORMAT

There are 17 instruction opcodes for the FT-818, listed in the chart on next page. Many of

these opcodes are On/Off toggle commands for the same action (e.g. "PTT On" and "PTT

Off". Most of these commands require some parameter or parameters to be set. Irrespec-

tive of the number of parameters present, every Command Block sent must consist of five

bytes.

Accordingly, any CAT control program must construct the five-byte block by selecting the

appropriate instruction opcode, organizing the parameters as needed, and providing un-

used "dummy" Eargument bytes to pad the block to its required five-byte length (the dum-

my bytes can contain any value). The resulting five bytes are then sent, opcode last,from

the computer to the FT-818 CPU via the computer's serial port and the transceiver's ACC

jack.

All CAT data values are hexadecimal.

Constructing and Sending CAT Commands

Example #1: Set the VFO frequency to 439.70 MHz

Per the CAT command table, the opcode for "Set Frequency" is 01. Placing the opcode

into the 5th data bit position, we then enter the frequency into the first four data bit posi-

tions:

DATA1

Send these five bytes to the transceiver, in the order shown above.

Example #2: Turn the Split Mode "On"

Per the CAT command table, the opcode for "Split On/off" is 02. Placing the opcode into

the 5th data bit position, we then enter dummy values into all other parameter locations:

DATA1

CAT System Programming