Cat System Computer Control - Yaesu FT-747GX Operating Manual

6. CAT
SYSTEM
The CAT (Computer Aided
Transceiver)
System
in the
FT-747GX allows control
of
frequency, mode, memory and other
settings
by
the
operatorts external personal
computer.
Serial data
is
passed
at TTL levels (O
and
5V)
via
SO (serial output) and
SI
(serial
input) pins
2
and
3 of
the CAT jack on
the
rear
panel
of
the
transceiver
at
4800
bits/sec
(CAT jack pinout is
shown
on
page
8).
Each
byte
sent
consists
of
one
start
bit,8
data
bits
(no parity bit)
and
two stop
bits:
: 3r2^
i?os6i2os^:
I
+
t
-Hi)l+
;iror.-''
-'
I
I sroP
' BIT
i-?
!
Data Format
for I
Character
All
commands
sent from the
computer
to
the
transceiver consist
of
blocks
of five
bytes
each,
with 50
to
200ms between
each
byte.
The last byte sent
in
each
block
is
the
instruction opcode,
while the
first
four
bytes
of
each block
are
arguments:
either
parame-
ters for that
instruction,
or
dummy values
(required
to
pad
the block out
to
five
bytes):
-; l-
lo..
-
zoo..
Data Format
for
1 Block (5
Characters)
There
are
fourteen instruction
opcodes for
the
FT-747GX,
listed
in
the upper table
on
page 29. Notice that
several
instructions
(UP500K, DN500K
and UPDATE) require
no
parameters. However,
every
Command Block
sent
to
the
767 must always consist
of
five
bytes.
COMPUTER CONTROL
The CAT control
program
in
the
computer
must construct
the 5-byte block,
organizing
the
parameters,
if
any,
and providing
unused
(dummy) argument
bytes
for
padding.
These
will be
ignored when
such instructions
are
executed,
so they
need
not be
zeroed.
The
instruction opcode
is
then placed
at
the
end
of
the block,
and
all
five
bytes are sent
to
the SI
serial input
pin
of
the CAT jack
on
the
transceiver.
EXAMPLE:
Set
14.25000
MHz as the
current
operating frequepcy;
( I
)
Bu
i
ld the four
argument
by
te
values
from the
desired frequency
by
breaking
it
into 2-digit
blocks: technically referred
to
as
"packed decimalrr format. Note
that
a
leading
zero
is
always required
in
the
hundreds-of-MHz place (and
another in
the tenrs-of-MHz
if
below 10
MHz).
0r42s000
Step
(1)
0l 42 50
00
Step (2)
00h
50h
42h
Olh
OAh
LSD
MSD
FREQ_SET
Frequency
Parms
Opcode
(2)
Now
REVERSE
the order
of
these
bytes,
and add
the appropriate instruction
byte
on the end. The small
I'hrrs following
each byte value indicate
hexadecimai
(base 16) values (which
in
packed
decimal
format use the
same
digits as
their
decimal equivalents).
(3)
Send
the five
bytes
to the
transceiver,
LSD (least significant digit) first (left-
to-right as
above).
Notice that there
is
space
for a
tenrs-of-Hz
digit in the
frequency parameters,
although