Computer Control of ICOM Amateur Gear
Carl Clawson, N7KBV
General Description
Several ICOM products feature a built-in computer
interface connected to a 1/8" phone jack on the rear panel.
However, ICOM gives no information about this interface in
the instruction manuals that I've seen. The information
exists within ICOM, and my dealer managed to get it for me.
This interface, called the "CI-V" by ICOM, is standard
on the following models: 735, 761, 275, 375, 475, and
R7000. Earlier models used the CI-IV parallel interface,
which can be connected to CI-V by ICOM's UX-14 converter.
Models using the CI-IV are the 751, 271, 471, 1271, and R71.
The information I got from ICOM was written with the 735 in
mind, but a listing of a BASIC program to control the R7000
was appended. I believe it will help with the other models,
too. The control codes and data format should be the same
for all of them.
The computer interface allows you to do such things as:
- Set and read the frequency and modulation mode
- Set VFO A, VFO B, or memory mode
- Select memory channel
- Store displayed frequency into memory
- Transfer displayed memory-mode frequency to a VFO
Even without a computer, you can run a cable between
the remote control jacks of two rigs, and whenever the fre-
quency or modulation mode of either is changed, the other
will track it if possible. (If the rigs have incompatible
frequency coverages, like the 735 and R7000, funny things
can happen.)
The interface is bi-directional, using TTL levels on a
single line for sending and receiving serial ASCII data.
You may need an appropriate hardware interface to convert,
for example, RS232 to TTL. (I understand that Commodore
computers have TTL inputs and outputs so that no interface
is needed with them.) I used the Motorola MC1488 and MC1489
chips powered by two 9-volt batteries to interface to my
RS232 line. Appendix 1 lists the pinouts used for this
interface. If you'd rather buy something, ICOM sells the
model CT-17 level converter for RS232.
The interface uses a "carrier-sense, multiple-access
with collision detection" local area network protocol, so
that multiple rigs can be connected in parallel without dif-
ficulty. Thus, you can use the same RS232 line and level-
converter interface to control many rigs. Each rig must
have a unique address, which is set by internal jumpers.
Each model comes factory preset to its own address, which is
04 for the 735 and 08 for the R7000. Appendix 2 has infor-
mation on the jumper settings.
I will use the words "receive" and "send" to refer to
data transmissionhe word "rig" to mean an ICOM product using the
CI-V interface.
The rigs send and receive data in variable length pack-
ets, which are formatted as follows:
Byte # Contents
1 hex 'FE' (i.e. 11111110 binary, 254 decimal)
2 hex 'FE'
3 <RX>
4 <TX>
5 <Code>
6-n <BCD data of variable length>
n+1 hex 'FD'
The two hexadecimal FE bytes signal the beginning of a
packet, and the FD byte signals the end. <Code> is the con-
trol code sent by the computer to the rig, which determines
the action that the rig will take. In some cases, the
receiving rig will include a control code in its response to
the sender; see the section "Control Codes and Responses"
below. <TX> is the address of thng sent.
When a rig responds to a data packet, it addresses that
response to the <TX> in the packet. Thus, if your computer
(Of course, the computer can lie about its address and trick
one rig into talking to another!) Your computer should use
its own uniqu There are two control codes that can cause any rig on the
network to respond when sent with <RX>=0; I discuss these below.
Bytes #6 through #n contain any data required by the
control code, in BCD format with 2 decimal digits per byte.
ing the
1-Hz and 10-Hz digits. These digits are sent even if they
are not used by the rig, so that the data format is the same
for all rigs regardless of their frequency coverage and
MHz. This is broken up into two-digit groups:
25 13 24 40
It is then coded in BCD. In other words, consider each
digit group to be a hexadecimal number instead of decimal.
,
FE FE <RX> If you have more than one
rig on the network you may
collision has occurred. Each rig, when sending, monitors
the interface. If it does not receive exactly what it sent,
then a collision occurred, sending a packet, it will
wait until the network is idle,
then send the jammer code. A rig that receives this code
will realize that a collision has occurred and ignore the
previouontrol
ports are bi-directional, your computer wi
Control Codes and Responses
Most of the following codes are adesses an acknowledgement packet to the <TX>
contained in the control packet. The first two codes, 00
and 01, can be sent to the "group call addres nowledgement. without computer intervention. Rigs can be inhibited from
sending and receiving group call packets by an internal
jumper. See Appendix 2 for more details. These codes can
also be sent with a specific, non-zero <RX>, in which case
they will be recei
00 Set frequency. See above foode desired.
Data Mode
0
02 Report tuning range. No data required. The rig will
report its frequency limits in the format
FE FE <RX> <TX> 02 <upper limit> 2D <lower limit> FD
(Hex 2D is the ASCII hyphen.) According to ICOM, some
rig format
04 Report modulation mode. No data required. The
return an additional byte indicating the bandwidth.
h> FD
The bandwidth codes are:
Data Bandwidth
01 Width 1 (widest)
02 Width 2 (narr
05 Set frequency. The data format is given above. If the
data contains fewer digits than the rig uses, the
digits sent will be changed and the rest will remain
within its tuning range, it responds with a packet con-
taining the d If it didn't like the data, it responds with the data
"FA":
These acknowledgement codes are used by all following
commands.
cy data by
sending the "FA" acknowledgement and: 1) If the quency data that is more than 30 MHzne byte is sent, it sets the
mode per the above table. If tw 07 Set VFO status. If no data is sent, the rig changes
from MEMORY mode to VFO mode. If data 00 or 01 is
sent, the 08 Set memory channel. If no data is sent, the rig
changes from VFO mode to MEMORY mode. If BCD channel
data is sent, the rig changes to that memory channel.
09 Store displayed frequency and mode into displayed
memory channel. No dat to a VFO. No data required.
I will give a few examples of codes and responses for
the 735. The 735 is at address 04 and the computer nnel, and code 03 to read the frequency).
Assume the 735 has the frequency 7.12750 MHz stored in
memory #1.
Computer to 735:
FE FE 04 02 08 01 FD
735 to computer:
FE FE 02 04 FB FD
Computer to 735:
FE FE 04 02 03 FD
735 to computer:
FE FE 02 04 03 00 75 12 07 FD
Now let's change the frequency and mode to 14.02500 MHz USB
(codes 05 and 06).
Computer to 735:
FE FE 04 02 05 00 50 02 14 FD
735 to computer:
FE FE 02 04 FB FD
735 to computer:
hanged result back into memory #1. This
channel is already displa
FE FE 02 04 FB FD
This is an easily built converter that will run
hour or two for about $10. The converter uses two inexpen-
sive, needed are a box, connectors, a power
nicads off of your RS232 line.
The pinouts are as follows:
For e 1488 -
Pin Connect to
1 ICOM remote jack center conductor
3 RS232 pin 3 (RD)
For the 1489 -
3 ICOM remote jack center conductor
7 Ground
14 +V
Ground pin
Appendix 2 -- Jumper Selections
There are jumpers in the ICOM rigs to set the device
address, baud rate, and to enable the group call feature.
You must look on the schematic to find them. The jumper to
enable the gr transceive enabled.
I have specific information the 735 codes and the schematic.
For the 735 -
The jumpers use lines labeled DB0 through DB5 a nector J22 on the PL board. Lines DB0 through DB2 set the
device address. Line DB3 is the transceive enable. The
DB4 DB5 Baud
0 1 1 300
The 735 is set at the factory to add frequency or modulation mode manually. You will receive a
group call packet that contains as its 4th byte the address
of the rig.