Missing 1.5 stop bits

[reconbot]

This will change the data type of stop from an octet to something else, but this is a fairly common
(although not as common as 1 or 2) setting with hardware devices.

https://electronics.stackexchange.com/questions/78788/what-is-the-meaning-of-half-bit-in-this-context

[reillyeon]

How is support for 1.5 stop bits handled in cross-platform software? It appears that this mode is only supported in the POSIX API for devices operating with 5 data bits. It doesn't clear from the Windows documentation whether there is a similar restriction.

[DarDoro]

https://docs.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-dcb
ONE5STOPBITS =1.5 without any further restrictions.

For the receving party declared as 1 stop bit it wiil be looking like slight delay between bytes.
But for writing 2 stop will be needed or performing write byte by byte to simulate slight delay.

How is support for 1.5 stop bits handled in cross-platform software?

As a case corner : 1, 2, 15 ?

[reillyeon]

Is this actually used in practice? On Windows it looks like it is only supported when using 5 data bits, a similarly unusual configuration. Can you point at any hardware out there that requires it?

[DarDoro]

Can you point at any hardware out there that requires it?

No

This requires zero to minimal effort, as 1,2 already must be converted to native platform enums.
And it was reported by reconbot ...

[reillyeon]

Writing code is never zero effort and the lack of cross-platform support for this mode makes me very reluctant to specify. If a developer came to me with an example of a device which required this mode then I could look at the ecosystem that device was part of to get a better understanding of how this configuration is managed despite the apparent lack of cross-platform support and that would provide the background I feel I need in order to add this to the specification. Without that I am working in the dark and that tends not to go well.

[larsgk]

Interesting, according to https://en.m.wikipedia.org/wiki/Serial_port "The number of data bits in each character can be 5 (for Baudot code), 6 (rarely used), 7 (for true ASCII), 8 (for most kinds of data, as this size matches the size of a byte), or 9 (rarely used). 8 data bits are almost universally used in newer applications. 5 or 7 bits generally only make sense with older equipment such as teleprinters." And "Electronic devices usually use one stop bit. If slow electromechanical teleprinters are used, one-and-one half or two stop bits are required." TIL :)

…

On Fri, 23 Jul 2021, 02.54 Reilly Grant, ***@***.***> wrote: Writing code is never zero effort and the lack of cross-platform support for this mode makes me very reluctant to specify. If a developer came to me with an example of a device which required this mode then I could look at the ecosystem that device was part of to get a better understanding of how this configuration is managed despite the apparent lack of cross-platform support and that would provide the background I feel I need in order to add this to the specification. Without that I am working in the dark and that tends not to go well. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#48 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAHXXFRJ5TWTW7RTZZSJDYLTZC4TVANCNFSM4FWWD35Q> .

[reconbot]

I ain't fighting for it, but there's a lot of old hardware out there that people need to keep working.