Devices that only reply with an ACK?

I usually use a function to send the string to the projector. It simultaneously copies it to a 'sent_string' variable so when I get a reply from the device, I compare it with the last string sent to know what to do with it. I have a couple Sharp XG-PG50 projectors that only reply with a number if your asking for the input or lamp hours.

Even replying with a single number is better than just an ACK. I tend to treat them like IR devices and do all my tracking in the module depending on what I sent it. I don't concern myself with feedback at all in such cases; I'm not a fan of faking feedback.

jweather wrote: »

Don't forget that "ACK" could mean "Received your message, checksum is okay, but I'm going to ignore it because I want to." It doesn't necessarily mean the projector actually did anything in response...

I've always thought the choice of the term 'ACK' was a bit of a problem. I know it means 'ACKNOWLEDGE' and all that. But, to me it sounds to much like something choking.

By the way, I"m with Dave. If it doesn't send me real feedback, it's an IR device in my mind.

I tend to cheat, and use the ACK as a pointer to send a status command ( basically instead of a timeline )
I have found that most devices that only have a ACK respsonse to an action have a dedicated status command, so it tends to work in most cases.

But add me to voice of dissent for protocol writers that can not be "bothered" it seems to flesh out a proper protocol. Maybe they should be made to implement their own protocols and see how they like it

Is there no polling command?

Usually for those, I use a timeline, to poll once for all the possible things that I am tracking.

data_event[dvDevice]
{
string:
{
select
{
active(find_string(data.text,"'Ack'",1)):
{
timeline_create(TL,TLarray,length_array(tlarray),timeline_absolute,timeline_once)
}
}
}
}
timeline_event[TL]
{
switch(timeline.sequence)
case 1:
{
send_string dvDevice,"'query1',13"
}
Case 2:
{
send_string dvDevice,"'query2',13"
}
}


This way everytime you are getting an ACK back from a device you time the controller to go out and check to see what has changed.