Grex Hardware Conference

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Grex Hardware Item 7: Help with one of those free terminals with no docs...
Entered by ragnar on Mon Aug 19 23:07:20 UTC 1991:

  I just picked up a free terminal and I want to get it working!
(come on now, I know all of you have done this yourselves...)

It's a Heathkit terminal, model HI98, and seems in good working order.
My problem is in communicating to the modem. The port on back of the
terminal is a DB-25 connector, like RS-232, but it's a *male* jack
wheras it usually female for an rs-232 device.  The port is labeled
"DTE".  What is it?

10 responses total.

#1 of 10 by jdg on Tue Aug 20 01:45:10 1991:

DTE is telephonese for "Data Terminal Equipment."  What you have there is
a 25 pin RS-232.  Run down to your local cable store and obtain a cable
of the correct sex.

#2 of 10 by choke on Tue Aug 20 03:03:17 1991:

Your modem is what is called 'DCE' for data communications equipment.

#3 of 10 by ragnar on Tue Aug 20 11:09:51 1991:

I got the sex changer right away, still no response from mr modem
Don't see any dips either, I'll have to try and take some panels off...

#4 of 10 by bad on Tue Aug 20 11:42:24 1991:

No dips? No dips?!
Mr. Straight line...
Hmmn...

#5 of 10 by klaus on Tue Aug 20 12:11:19 1991:

Maybe it's time to try a nul-modem adapter (or simply switch the wires
going to pins 2 and 3 as well as those going to pins 4 and 5.)
If I were in your shoes though, I'd save some time and call HeathKit.
I've been treated very well by their tech. assistance people.

#6 of 10 by fes on Tue Aug 20 13:18:26 1991:

You might want to try a loopback connector (I can get you the pinout to build
one or can loan you one for a short period of time - IF I can find mine). This
will allow anything typed out to bounce back to your screen. It's possible that
you're running at some baud rate that is incompatible with your modem. You
should normally see crap bouncing back from the modem if that's the case but
I'm not sure that that's guaranteed. I have played around with some ancient
Zenith terminals in the past and I seem to remember a set of dip switches under
the cover near the back.

#7 of 10 by mdw on Wed Aug 21 18:08:49 1991:

DTE means it's already opposite in polarity to modems, which are
always DCE's.  So a "straight through" cable is right.  In fact,
the identical cable that works with an IBM-PC should work with
the heathkit.

You'll definitely want to see that the baud-rate is set right.
Also parity -- 7 bits, even, would be best.

It would be good to try it it out with a modem that has blinky
lights -- even at the wrong baud-rate, you should be able to make
"SD" light up on the modem.  Also "TR" should be lit.  If the
modem has dip switches to enable/disable "CD", you might experiment
with that -- the terminal may be refusing to send data if CD isn't
asserted -- seems unlikely, but not impossible.

#8 of 10 by mcnally on Fri Aug 23 04:15:59 1991:

  If the modem doesn't have dip switches, chances are there's a set-up
mode accessible by hitting some key combination (like maybe a set-up key..)

#9 of 10 by mdw on Fri Aug 23 16:41:49 1991:

I assume you meant "if the TERMINAL"...

#10 of 10 by mcnally on Tue Sep 3 05:27:54 1991:

 yep..  that's what I meant..

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