Yaesu FT-747GX User 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

Yaesu FT-747GX Specifications

General

Brand	Yaesu
Model	FT-747GX
Category	Transceiver
Language	English