tony duell ard at p850ug1.demon.co.uk
Sat Dec 5 10:17:51 CST 2015

> >
> >> TU58 's is ready to test. I tried it in a spare serial port on a VS 3100.
> >> Result nothing. I suspect the port is 423 and the tu58 232.
> >
> > Actually the TU58 serial port has the differential driver and receivers used
> > on the later serial ports. It should talk to DECs version of RS423 with no
> > problems at all.
> Not only that, but you can normally go between 232 and 423 with no
> problem. I suspect there is something else wrong with the port, or the
> software...

So do I....

Firstly, what are the jumpers on the TU-58 board? The default is 38400 baud, which
is probably why Rod sees it doing something sometimes at that baud rate.

A lot of laptop serial ports (and USB-serial converters) are marginal at best. I've had
ones that won't drive the capacitance of a couple of metres of cable reliably at 4800
baud, let alone 38400 baud. 

If it were mine I'd be looking at exactly what was flowing into the UART on the TU58 with
a logic analyser. 


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