[BRLTTY] Focus 1 70 display and USB to serial adapter: possible connecting this scenario?

[Dave Mielke]

[quoted lines by Hammer Attila on 2024/12/24 at 17:12 +0100]

>What is the value in MS that you think doesn't cause too much latency for
>Focus displays, whether it's a connection happens a traditional connection or
>operation via a USB converter (using a USB to serial converter)? 

I'm experimenting. That's why I'm suggesting to start with 200ms. If it works then we can try lowering it, and if it doesn't then we can try raising it.

>What the maximum value this code line related with accepts the driver?

Large. It's an integer. So don't worry about any limits. If we get up to, say, 2000 (so two seconds) and it still isn't working then the issue is probably something else.

As another experiment, though, you may wish to temporarily set it up to 30 seconds (so 30000) in order to give yourself enough time to do the stty -a and know that we're getting the actually configured settings.

>What is the basic operation? For both connection types, does the current
>driver constantly try to establish a connection, or does it wait for e.g. 50
>or 100 milliseconds before trying again?

When the fs driver starts with a serial connection, it probes the device three times. These probes are 100ms apart. If, after three probes, it gets no response then it shuts down and waits five seconds before trying again. The ready delay only applies to a wait before the first of the three probes, i.e. between when the device is configured and when data transfer begins.

>But real serial hardvare connection why not happens this issue, or happens,
>but not possible detecting this with user level because more faster the
>driver establish the connection a traditional serial cable between the real
>serial port and the display serial port?

The real device probably configures "instantly" whereas the adapter might be playing games with buffers and, therefore, takes a noticeable amount of time. Just a guess but it wouldn't syurprise me if the manufacturer of any given adapter plays a dirty trick or two in order to keep its price down. A different adapter may well perform differently.

-- 
I believe the Bible to be the very Word of God: http://Mielke.cc/bible/
Dave Mielke            | 2213 Fox Crescent | WebHome: http://Mielke.cc/
EMail: Dave at Mielke.cc  | Ottawa, Ontario   | Twitter: @Dave_Mielke
Phone: +1 613 726 0014 | Canada  K2A 1H7   |

http://mielke.cc/xmother.html (Letter from a Feminist ex-Mother)