Advertisement
APPENDIX C _ _ _ _ _ _
Making an RS232-C
Interface Cable
If you are making your own serial interface cable, there are
certain requirements to be satisfied for proper communica-
tion between the computer and the
printer.
You've already
set the switches and jumper plugs that regulate protocols,
baud rates and character bits. Now, in order to make a cable,
you must first know how your computer is configured
-
as
Data Communications Equipment or Data Terminal
Equipment.
REMINDER:
Cabling may already be shown for your
computer system in Appendix D.
Most computer systems are designed as Data
Communi-
cations Equipment (DCE) so they act as the
host-
in control
of the printer, so to speak. The Microline 92 and 93 are Data
Terminal Equipment (DTE). They expect to receive in-
structions and commands from a host (DCE). So when the
computer is a DCE and it's connected to our printer, every-
thing works out fine.
However, like with everything else, there are always excep-
tions to the rule. A few computers on the market today are
set up as DTE's. You can't have a DTE communicating with
a DTE, so you have to do some rewiring to "fool" the
computer into thinking that the printer is a DCE
.
There is one obvious problem. How will you know what your
computer
is-
a DCE or a DTE? It's doubtful that your
computer documentation will specify it, so once again, we
recommend that you refer to Appendix D where we show
you how to configure several of the popular computers to
operate with the ML92 and 93
.
If your system isn't there,
try wiring it as a DCE. It won't hurt to run it that way, in
fact, chances are you'll be right. Then if it doesn't work, add
the additional wire to configure it as a DTE.
Before we show you sample high speed RS232 -C cabling
configurations, here is an overview of the signals to be
satisfied on the printer's side. Since requirements vary from
one computer system to another, we can't identify the
connections your computer requires or even which pins they
represent. However
,
our sample configurations may assist you
in sorting it all out.
C-1
Advertisement
