Re: 1-wire to USB converter that can use 1820s directly

["Rod Speed" <rod.speed.aaa@xxxxxxxxx>]

Dave Houston <nobody@xxxxxxxxxxxx> wrote
> Rod Speed <rod.speed.aaa@xxxxxxxxx> wrote

>> Serial ports done that way arent that easy to support in VBA
>> either, support for non standard serial ports is pretty poor.

> For software on the PC there is absolutely no difference between
> a serial port on a PCI card, a virtual serial port (such as those
> used with USB-serial or those used with TCP/IP serial servers).

There is however a real difference between the
standard com ports and the other ones from VBA.

> They are seen as if they were serial ports on the motherboard.

Its more complicated than that in practice,
most obviously with the IRQs etc.

> The advantage is that legacy software can make use of them.

> One potential glitch is that legacy software may only
> support COM1-COM4 while the ports may be identified
> as COM1-COM99 (you can rename them).

Precisely and thats the problem with VBA.

I did in fact write my own driver for a special serial port
that I kludged up using an ISA card with no IRQ at all,
because it was a special purpose serial port that was
only ever used for output only to a datawatch, but I
dont want to go the serial port route because it would
be convenient to be able to use the laptop which has
no serial ports at all for debugging, and the PVR which
I may well end up with the logging on because its on
the UPS, doesnt even have any free PCI slots left,
because its got 4 digital TV cards, a lan card and
a decent dual head video card using all the slots.

> If you are writing your own software, it's fairly simple to
> enumerate all of the ports and make them available to your
> software - do a Google search on "VB enumerate serial
> ports". You should be able to use the same code in VBA.

It isnt in fact quite that simple from VBA.

> Another potential glitch is that USB-serial converters are not all
> created equal. Some do not handle the handshaking lines. The
> only fix is to use one that does. The CP2102 handles everything.

Or dont bother with serial at all, just use a pure USB approach instead.

Cant see the point in bothering with serial at all if a standard
commercial USB/1-wire converter/adapter will do the job fine,
and I havent seen any evidence that it wont.

Going that route allows me to use the laptop for debugging,
use the PVR for the long haul, and is a lot simpler and more
elegant than any serial prot approach will ever be. With a
lot more future too as serial ports sink beneath the waves.