20 Feb
2013
20 Feb
'13
1:28 p.m.
On 2/20/2013 12:43 PM, Ethan Dicks wrote:
On Wed, Feb 20, 2013 at 1:19 PM, Jim Stephens <jws
at jwsss.com> wrote:
If you can find them (still) and the input side you use itself doesn't
have a problem, one thing we used to do on any oddball lashup was to buy
a small, 64k or so serial FIFO buffer. it eliminated all sorts of
handshake problems with people trying to hook up things to our 8ways
(Microdata Reality serial port). Also most times used one on output to
serial printers, though the printers got better over the years.
We did have one instance where the user we sold a printer to started to
complain about getting a short page or so after many months of smooth
operation. Turned out they had never printed a report full bore @ 256k
in length prior to that, and there was a problem with a setting that
dropped everything after the first 256k or so. They had printed > 256k
of course, but the flow control and pacing of the system had never
blasted the 256k in one burst.
that was entertaining.
Jim
Nick
have you looked to see that the levels are anywhere near the correct levels
when connected to the 680? I don't know about the unit you have, but I'd be
sure that you have +- 10v or so when you are connected. I would think that
there would be a > 0 chance that they cheat on the level and drive on the
USB -> serial ports.
I have definitely seen that be a problem with modern USB
serial
adapters and older 1488/1489 RS-232 interface circuits. In
particular, I was trying to get a laptop to talk to an original,
un-upgraded Bridgeport II mill (with a real DEC KD-11H M7264 CPU) with
a hand-built round Tyco cable adapter, and it was totally no-go until
I found a desktop machine with a "real" serial port. Like magic, it
just worked at that point (with the same bit rate, parity settings,
etc). I didn't check what the USB serial dongle was outputting
(limited tools at the shop site) but I never did get it working with
the mill.
-ethan