Ok, ICOMs CI-V it a very usefull and very simple protocol.

In this posting we will look at how we can figure out if the radio is in RX or TX and switch it to RX or TX.

First the CI-V protocol is a handshake protocol, someone must initiate the conversation and then who ever he is talking to will respond (sorry about the BAD english sometimes I am a frenchy and from the GREAT WHITE NORTH :P ) if available.

The structure of a CI-V exchange is simple enough;

Header (Two FE)
address of the destination
address of the sender
sub command
Data (optional)

So if I want to know what is the radio doing (RX or TX) I would use the 1C command (see table below) and send;

FE FE (HEADER) 94 (Address for a 7300) E9 (address I chose for my applications also known as Controller) 1C (Command to reques/control tranceiver, tuner and other functions (see table attached)) 00 (Subcommand for RX/TX status/Control) FD (Trailer, notice NO DATA! very important)


FE FE 94 E9 1C 00 FD

Note that E9 is just an address I use to make it easier for locate my stuff, E0 is more common, this can be anything that is not aready assigned on your CI-V buss.

the 7300 will respond like this;

FE FE E9 94 1C 00 00 FD

Note that now DATA is present aka our resonse; a 00 means (see table) I am in Receive, 01 TX.  Also you noticed that the addresses are reversed, E9 94 thus 94 (7300) is responding to E9 (application).

Ok what if I want to remotly put the radio in TX.

you remember the DATA wasnt used in my command above, thats because I was doing a query, well what if I use it! if I were to put a 01 in there then I would be requesting the radio to transmit, thus;

FE FE 94 E9 1C 00 01 FD

so now instead of asking a status I am sending a command!

The response changes when you do this, the radio will now ACKNOLEDGE (ACK or ICOMs FB I like to remember this as FINE BUSINESS!) or return a NEGATIVE ACKNOLEDGE (NACK or FA) to the command.

in the second table below you see the format of these.

so if I send a GO TO TX command

FE FE 94 E9 1C 00 01 FD

if it does it will respond with ACK (FB) ;

FE FE E9 94 FB FD 

But if for ANY reason it can not it will respond with a NACK (FA);

FE FE E9 94 FA FD 

That was an INTRO,  I will try to go into more advance commands later.

Hope this helped :-P

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1C command set
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ICOMs CI-V handshake protocol,


Richard VE2DX
Only the Best ICOM, ERC and HRD 
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Richard VE2DX, Jesus Island, PQ-014

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