THE LIGHTS ARE ON, BUT...
The bane of my life is RS-232 communication. This one area
has caused more wringing of hands and tearing of hair than
anything else. And while just plain RS-232 to RS-232
hookups are bad enough, the addition of modems makes things
worse. If the modems are high speed, data compressing
models, I start quivering before the cables are even hooked
up.
There was a time when I thought that my problems could be
alleviated by an increase in knowledge. I felt that I
really didn't know enough about RS-232 in general and modems
in particular, and that this knowledge gap was contributing
to my confusion and despair. It seemed logical to assume
that a liberal application of books, tools and playing
around could only bring good results.
Well, I have the books, and have read all about MNP and
V.42bis. I have puzzled over Phase Shift Keying and
Quadrature Amplitude Modulation. I've bought Gender
Changers and Null Modems and Breakout Boxes, along with a
horribly expensive crimper that attaches modular plugs to
phone wire cables. I have played with cables and modems and
software of all descriptions. In short, I have given myself
a short, intensive course in the theory and practice of
RS-232 communication.
Certainly these efforts have improved my understanding of
what is supposed to happen when two computers reach out and
touch each other with their DB-25's. Unfortunately, what is
supposed to happen is generally not applicable to life in
the real world. I still find myself typing AT commands into
stubbornly unresponsive modems or watching garbled and
unreadable messages scroll up and down totally confused
screens.
One of the most frustrating situations is when two modems
have been carefully matched ,lovingly configured and
quite properly introduced to each other. They have
accomplished their ritual handshaking, exchanged squeals of
delight, and have settled down with all the proper lights
aglow, seemingly throbbing in anticipation of the joyous
exchange of data that is to come. They then refuse to
transmit or recieve even one single character. Frantic
conversations with my counter-part at the other end ensue.
"Yeah, my 9600 light is on- is yours?" "My keyboard is dead-
no, I think the whole system is dead!". Breakout boxes with
festive red and green leds are applied to no avail. Port
configurations are checked and re-checked. Accusations of
subscribing to sub-standard long distance services are
invariably bandied about, and when things get truly
desparate, the very integrity of the Operating System is
called into question.
In such situations, the modem happily retains the connection
with its mute friend, while the two of them gobble up
Message Units. Guard signals (+++), which are supposed to
summon the modem to attend to commands, are blithely
ignored. Nothing short of unplugging the phone is likely to
convince either modem that the intended mating has not
worked. The occasional blinking of a Data light only adds to
the mystery: if these two devices are talking, what on earth
are they saying?
I know exactly what they are saying: "It's that Lawrence guy
again- and we are REALLY driving him nuts this time!"
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