Cat System Computer Control; Reading Transceiver Status; Status Update Data Organization - Yaesu FT-990 Operating Manual

CAT System Computer Control
The CAT (Computer Aided Transceiver) System
in the FT-990 provides control of frequency, mode,
VFO, memory and other settings by the operator's
external personal computer. This allows multiple
control operations to be fully automated as single
keystroke operations on the computer keyboard.
Serial data is passed at TTL levels (0 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/ s. CAT jack pinout is
shown on page 7. Each byte sent consists of one
start bit, 8 data bits, no parity bit and two stop bits:
One byte, sent left-to-right
All commands sent from the computer to the
transceiver consist of blocks of five bytes each,
with up to 200 ms 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 parameters for that instruction, or dummy
values (required to pad the block out to five bytes):
I
4th Arg Byte
I
3rd Arg Byte
I
2nd Arg Byte
I
1st Arg Byte
I
Opcode
5-Byte Command Block, sent left-to-right
There are twenty-five instruction opcodes for
the FT-990, listed in the table on the next page.
Notice that several instructions require no specific
parameters. However, every Command Block sent
to the transceiver
must always consist of five bytes.
The CAT control program on the computer
must construct the 5-byte block by selecting the
appropriate instruction opcode, organizing the
parameters, if any, and providing unused
(dummy) argument bytes for padding (the
dummy bytes can contain any value). The resulting
five bytes are then sent, opcode last, to the SI serial
input pin of the CAT jack on the transceiver.
Example: Set operation to 14.25000 MHz;
0
First determine the opcode for the desired in-
struction (see the CAT Commands Table, next
page). These opcodes should be stored in the
program so they can be looked up when the
user requests the corresponding command. In
this case the instruction
is
"Set Op Freq.", so the
opcode is OAh. The small "h" following each
value indicate hexadecimal (base 16) values.
0
Build the four argument byte values from the
desired frequency by breaking it into 2-digit
blocks (BCD "packed decimal" format). Note
that a leading zero
is
always required in the
hundreds-of-MHz place (and another in the
ten's-of-MHz if below 10 MHz).
0
The resulting 5-byte block should now look like
this (again, in hexadecimal format):
Bvte Value
Content
of this
byte
OAh
Set
Main VFO
Freq.
opcode
01h
42h 50h
100's & 1's of MHz
10
,
5
&
1
,
5
1 O's of & 1 OO's of of kHz
MHz kHz
OOh
100's &
10's of Hz
0
Send these five bytes to the transceiver, in
re-
verse order from that shown above - from
right-to-left (see the Basic example on page 43).
Reading Transceiver Status
The
Update, Read Flags, Read Meter and Pacing
commands report various conditions to the com-
puter via the SO (Serial Output) line.
Update causes
the FT-990 to return 1, 16 or 1,508 bytes of Status
Update data, while
Read Flags obtains only the first
3 bytes (the Status Flags), plus 2 Model ID bytes
(09h and 90h), and
Read Meter returns the meter
deflection (0- OFFh) repeated in four bytes, fol-
lowed by one "filler'' byte (OF7h). Each returned
byte may be delayed by an interval determined by
the
Pacing command (0 to 255 ms in 1-ms steps).
This delay is initially zero until the
Pacing com-
mand is sent.
The
Pacing command allows returned data to be
read and processed by even very slow computers.
However, you should set it as short as your com-
puter will allow, to minimize the inconvenience of
the delay. Sending 1,508 bytes requires just over 3
seconds with zero-length delay selected, but over 6
minutes if the maximum delay is selected!
Status Update Data Organization
The 1,492 bytes of available update data are
organized as shown schematically after the com-
mand table. Aside from the
Read Flags command,
different portions of this data can be returned in
blocks of 1, 16 or 1,508 bytes, depending on the
parameters of the Update command sent by the
computer. The details of these commands follow
the descriptions of the data.
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