figuring out Serial Port pins on an RJ15 connector

[Sam Kaan]

I have recently picked up a PCMCIA Serial card, ie. this card provides
a hardware serial port (RTS,CTS etc). However the card is made by
Socket and proprietary for a Compaq laptop, in that instead of having
a DB9 connector coming out, it instead have an RJ15 connector as the
serial connector. Has anyone used this before and do you know how to
adapt the pins to connect it to a DB9 adapter so it will be a normal
DB9 serial? I picked it up real cheap so its worth a try considering
its only be used for a short time. A "real" pcmcia serial card costs
a bundle.

By the way worst comes to worst, I would probably have to hook the
pins up to an oscilloscope perhaps and determine which pins is
CTS,RTS,TX,RX etc. Is this a feasible thing to do or do you see
obstacles. Is there a strategy/algorithm to determine what pins is
which? Unfortunately I no longer have one of those external modems
where those LEDs labelling TX,RX etc, or this would have been real
easy.

 

[Dan Barlow]

By the way worst comes to worst, I would probably have to hook the
pins up to an oscilloscope perhaps and determine which pins is
CTS,RTS,TX,RX etc. Is this a feasible thing to do or do you see
obstacles. Is there a strategy/algorithm to determine what pins is
which? Unfortunately I no longer have one of those external modems
where those LEDs labelling TX,RX etc, or this would have been real
easy.

You can get the "christmas tree" RS232 diagnostic bit for about $15.
Outputs should be at either + or - 12V. Inputs may have pull-ups/downs?
But the outputs are specified to provide a good amount of current,
so a LED with a resistor is enough to figure it out.
You could go so far as to use DEBUG to twiddle the port registers.
-Dan Barlow

 

[Ken Taylor]

I have recently picked up a PCMCIA Serial card, ie. this card provides
a hardware serial port (RTS,CTS etc). However the card is made by
Socket and proprietary for a Compaq laptop, in that instead of having
a DB9 connector coming out, it instead have an RJ15 connector as the
serial connector. Has anyone used this before and do you know how to
adapt the pins to connect it to a DB9 adapter so it will be a normal
DB9 serial? I picked it up real cheap so its worth a try considering
its only be used for a short time. A "real" pcmcia serial card costs
a bundle.

By the way worst comes to worst, I would probably have to hook the
pins up to an oscilloscope perhaps and determine which pins is
CTS,RTS,TX,RX etc. Is this a feasible thing to do or do you see
obstacles. Is there a strategy/algorithm to determine what pins is
which? Unfortunately I no longer have one of those external modems
where those LEDs labelling TX,RX etc, or this would have been real
easy.

I assume you have the drivers and such for the card, so the easiest thing I
can think of is to use something like VB to actually manipulate the control
lines. You should be able to find CTS, DTR and Rx/Tx easy enough, the rest
may take some playing.

Ken