20 Feb
2013
20 Feb
'13
12:43 p.m.
On Wed, Feb 20, 2013 at 1:19 PM, Jim Stephens <jws at jwsss.com> wrote:
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