Yaesu FT-712RH Operating Manual page 40

Data Format for 1 Block (5 Characters)
There are five types of instruction opcodes for the FT-712RH listed in the Instruction Code
Chart on the next page. Notice that three of the instructions require no arguments.
However, every Command Block sent to the transceiver must always consist of five bytes.
The unused par-ameter bytes will be ignored when such Instructions are executed, so their
value is irrelevant (they need not be zeroed).
EXAMPLE: To set 445.50000 MHz as the current operating frequency;
(1) Build the four argument byte values from the desired parameter (frequency, in this
case):
(2) Convert the decimal frequency argument values into packed BCD (Binary-Coded-
Decimal, with two decimal digits encoded into each byte), and add the appropriate
instruction byte on the end. The small "W's below indicate hexadecimal (base 16)
values, which in packed BCD use the same digits as their decimal equivalents.
(3) Send the five bytes to the transceiver, MSD first.
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