Need help with Advantech PCL-740 serial card - test-drb@ccmp.vtda.org

18 Jan 2014

On Sat, 18 Jan 2014 12:00:01 -0600, you wrote:

...
 From: Jonathan Katz <jon at jonworld.com>

On Sat, Jan 18, 2014 at 10:22 AM, Charles
<charlesmorris800 at centurytel.net> wrote:
  I have an ancient (AMD K6, 300 MHz, Win XP)
desktop PC that I am
 trying to use to download RL02 diagnostics to my PDP-8/A via the TTY
 console port (20 ma current loop). 
Not familiar with this at all, but two things.

1) I remember being able to set IRQs on PCI slots in this era of
systems. Maybe you need to play with that?

2) Have you tried a protocol other than current loop on this ISA card
(like RS-232) to another system to see if it works? 
I suspect you are right - that the card is somehow not signaling the
PC that it is ready to accept data. But there are no IRQ conflicts
(card is jumpered to 12 and Windows is unaware of anything else using
12, or address 0210-7). The existing serial ports are on 03F8, IRQ5
and so forth. Although the PCI slots do have a "plug & play/Auto"
setting, I removed every card except this one and the problem is still
there!

Yes, I have tried RS-232. The problem is not the line
drivers/receivers... no data is appearing at the UART's TxD pin
regardless of which set of buffers it then goes to. And as I noted, I
did hard-wire the RTS, CTS, DTR lines and they are being sensed, and
do not appear to be telling the port to hold off.

This card has a controller chip by Lattice and the UART (and a small
amount of glue logic). No schematic information of course.

Will keep trying. Thanks for the help.