21 Jun
2005
21 Jun
'05
8:15 a.m.
Vintage Computer Festival wrote:
It's the baud rate then. Also, make sure you have
the serial connections
correct. I just used two wires: one for TX and one for RX. No other
control signals are required, and it works just fine. I used shielded
wire.
I would greatly recommend using a signal ground wire
(pin 7 on RS-232). You can get weird, unreproducible
problems without it. It can cause really hard problems to
trace down.
The ground between two different boxes can float about
enough to cause signal reliability problems. The float can
sometimes vary enough to generate random character
streams. The longer the distance between the boxes, the
more likely you will have problems.
But you normally don't want to connect frame grounds
(pin 1 on RS-232 cables iirc). You sometimes get an
amazing amount of current through the cables, even
enough to melt them.