On 16/11/2021 14:07, Sam W2JDB via wsjt-devel wrote:
I also wondering about the multiple
'ID' requests, is that your version of heartbeat ? Just wondering.

Hi Sam,

the Kenwood protocol does not respond to CAT commands that set things, so there is a problem with reading any invalid response ('?') since we have no way of knowing how long to wait for a response which may never come. Hamlib gets around this ambiguity with a simple device, after CAT commands that do not elicit a reply when they work, a basic command that does elicit a reply is sent. Then we can read a reply and either get the command failed reply (and discard the expected reply), or the expected reply from the second command. This simple technique means that CAT commands can proceed without any wait time, despite extra traffic being sent.

Other CAT protocols are more robust and always send either an ACK or NACK response to all commands, so with them there is no ambiguity.

73
Bill
G4WJS.



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