Man at B&Q wrote:
On Jul 12, 12:20 am, John Rumm wrote:
The Natural Philosopher wrote:
Clint Sharp wrote:
In message , "Dave Plowman (News)"
writes
I need a longish serial cable to get from the workshop computer to the
bench. Say 4 mtr. I already have the D connectors and wonder what
would be
the most suitable cable I have 'in stock' Only need the send and
return -
no 5v. Would balanced mic cable do - or two co-ax? I do have some decent
video co-ax but two would be a bit big to fit the D connector shells.
Almost whatever you have to hand, as long as it's shielded. 4 metres
is trivial if we're talking about RS-232.
IIRC the max length for RS-232 by the specs is about 15 metres.
Obviously, the speed is fairly important and lower speeds will work
better over longer cables but I've used 115k at ten metres and 19.2
over some silly distances (around 35 metres for a terminal) without
noticeable problems. Just pay attention to the shield and ground.
Used to run 19.2k around cat 5 to glass terminals - serious distances,
but couldn't get higher, so I assumed that the OP wouldn't;'t be able to
go much above 100k, which is what everyone else seems to say.
Many UARTs won't run more than 115K, so that is a fair bet ;-)

But many more do.

Gazillions of UARTS in microcontrollers will run way faster than that.
I've done 1mbit/s in a PIC, between two devices on a PCB.

Indeed - but most are 8250(A) or 16550 style devices in PCs and similar.
With the selected xtal these usually do about 50 - 115K bps.

Given a 68HC302 or similar with the embedded "communications element"
you can do all manner of exotica with the serial lines!

The crystal selection becomes critical at higher speeds if you want to
use "standard" baud rates.

Yup, there are not many choices if you want all the usual ones.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/