VX-1700 CAT OPERATION REFERENCE BOOK
CAT (COMPUTER AIDED TRANSCEIVER)OPERATION
CAT DATA PROTOCOL
Serial data is passed at RS-232 levels via the SI (Se-
rial Input) and SO (Serial Output) pins of the GPS
jack (pins 2 and 3, respectively) on the rear panel of
the transceiver. The serial data format is 4800 bits/
second; each byte sent consists of one start bit, 8
data bits, no parity, and two stop bits (4800, N, 8, 2).
CAT DATA (ONE BYTE, SENT LEFT-TO-RIGHT)
All commands sent to the transceiver must consist
of blocks or five bytes each, with up to 200 ms be-
tween each byte. The last byte sent in each block is
the instruction opcode, while the first four bytes or
each block are arguments: either parameters for that
instruction, or dummy values (to pad the block out to
five bytes).
5-BYTE COMMAND BLOCK (SENT LEFT-TO-RIGHT)
There are 15 instruction opcodes for the VX-1700.
Notice that several instructions require no specific
parameters, but every command block sent to the
transceiver must consist of five bytes.
The CAT control program in the computer must con-
struct the five-byte block by selecting the appropri-
ate instruction opcode, organizing the parameters, if
any, and providing unused (dummy) argument bytes
for padding (dummy bytes may have any value). The
resulting five bytes are then sent, opcode last, to the
SI (Serial Input) pin of the GPS jack on the rear panel
of the transceiver.
Example: Tune to 14.250.0MHz:
First, determine the opcode for the desired in-
struction (see the CAT command table). These
opcodes should be stored in the program so they
can be looked up when the user requests the cor-
responding command. In this case, the instruc-
tion is “Set Receive & Transmit Frequency” so
the opcode is “0Ah” (small “h” letters following
each byte value indicate hexadecimal (base 16)
Values).
Build the four argument byte values from the de-
sired frequency by breaking it into 2-digit blocks
(reversed BCD “packed decimal” format). Note
that a leading zero is always required in the “hun-
dreds-of-MHz” place (and another in the “tens-
of-MHz” place, if below 10 MHz).
The resulting 5-byte block should look like this
(again, in hexadecimal format):
Send these five bytes to the transceiver (Sent Left-
to-Right: 00 50 42 01 0Ah).
START BIT 0 1 2 3 4 5 6 7 STOP BIT STOP BIT
BYTE 1
ARGUMENT
BYTE 2
ARGUMENT
BYTE 3
ARGUMENT
BYTE 4
ARGUMENT
BYTE 5
COMMAND
OPCODE
BYTE 1
00
BYTE 2
50
BYTE 3
42
BYTE 5
0Ah
OPCODEDATA/ARGUMENT BYTES
BYTE 4
01
BYTE 1
00
0
100’s
Hz
0
10’s
Hz
BYTE 2
50
5
10’s
kHz
0
1’s
kHz
BYTE 3
42
4
1’s
MHz
2
100’s
kHz
BYTE 4
01
0
100’s
MHz
1
10’s
MHz
Page 3
Connected with , , , and .
GPS Data Input.
N/C (Lot. 1~25)
GPS Data Output (Lot. 26 & 27 :
When the firmware is updated.
GPS Data Output (Lot. 28~)
Connected with , , , and .
GPS Data.
Connected with , , , and .
Connected with , , , and .
Connected with , , , and .
N/C (Lot. 1~25)
GND (Lot. 26~)
GPS Jack
(As Viewed From Rear Panel)
