How can I parse that a device returns nothing / is switched off?

[Klaus]

I want to check whether a RS-232 device (audio mixer) is powered on or not.

If the mixer is on I can send a command "SET 8 1F 1B 0" and get a feedback "SET 8 1F 1B 0" from the mixer.

But how to parse if nothing is returned (the mixer is switched off)?

Maybe I am completely on the wrong path?

[Barry Gordon]

set a timer to time the response.  If the timer (let's say 2-3 seconds) expires then you could assume the device is powered off

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[Klaus]

Great, Barry! Sounds so easy. But I guess it needs some coding (I am still a "one-line-programmer" ...).

So I tried an "old-fashioned" way, which did the job:

Sent a command SET 8 1F 1B 0 to the mixer.

Receive a feedback with Regex (SET 8 1F 1B 0), OnMatch sets target d99 to 1.

With a start delay of 2 sec I send a command and JavaScript: CF.getJoin("d99" function(j,v) {CF.runCommand(null, (v=="1")? "command name to call home-page" : "Command name to call error-page"); });

I am just curious (want to learn) how it would look like using a timer and some coding. Easy?

[Vladimir Shabunin]

It can be done with JS. The deal is to declare some timerObject = null in global scope, on command sending use timerObject = setTimeout(<do thing in case if device is switched off>, timeoutInMs);   register FeedbackMatchEvent for your feedback regexp, that will contain code in case if you have receive reponse from device and if (timerObject !== null) { clearTimeout(timerObject); } 

So, study setTimeout/clearTimeout/CF.watch/CF.send if you want to implement it in js code.

вторник, 11 декабря 2018 г., 22:13:32 UTC+3 пользователь Klaus написал: