Modem Pin connection question

Archiver

I have a land-cell wirless modem with a standard RS232 DB9 port that
I would like to use with my BS2p40. I was reviewing information on
the CH1786 but alot of the wiring is different. I have used this
modem in the past by simply connecting it to COM1 on my computer and
it has worked great so I figure it must have "standard" pin
connections.

Does anyone have any ideas about what pins from the DB9 connector (on
the modem) I need to connect to the BS2p40 so that I can dial out as
well as call in using handshaking? If I can get the pin connections
straight I think I can modify the code from the CERMETEK.BS2 program
that Jon wrote. I have 9 pins available on the BS2p40.

Thanks in advance for any direction you can provide.

Kind Regards,
Eric

Archiver

That you can connect directly to your PC
means that the CH1786 platform you used is
wired as "DCE" -- Data communication Equipment.

Thus it 'talks' on RX (pin 2), 'listens' on TX (pin3).

If it has a buffer, it will raise CTS (pin 8) to +12
when it is okay for the BS2 to talk. It expects the
BS2 to raise RTS to +12 when it is OK for the Modem
to talk to the BS2.

It will raise DSR (pin 6) to +12 when the modem is
powered-up. It will raise DCD (pin 1) to +12 when
the modem has gotten another modem to answer the
phone.

You can force the 1786 to hang up by lowering DTR
(pin 4) to -12.

And of course, Ground MUST be connected (pin 5)
to your BS2 ground.

Note the +- 12 volt signals I have above assume
you are using a MAX232 or equivalent to drive the
modem. If you are using TTL directly to the
modem chip, then -12 maps to +5 volts, and +12
maps to 0 volts.

These are the RS-232 standard pins and useages.
You might get a 1786 data sheet, and verify that
these are correct for that chip.



--- In basicstamps@yahoogroups.com, "Eric Berg" <khufumen@y...> wrote:
> I have a land-cell wirless modem with a standard RS232 DB9 port
that
> I would like to use with my BS2p40. I was reviewing information on
> the CH1786 but alot of the wiring is different. I have used this
> modem in the past by simply connecting it to COM1 on my computer
and
> it has worked great so I figure it must have "standard" pin
> connections.
>
> Does anyone have any ideas about what pins from the DB9 connector
(on
> the modem) I need to connect to the BS2p40 so that I can dial out
as
> well as call in using handshaking? If I can get the pin connections
> straight I think I can modify the code from the CERMETEK.BS2
program
> that Jon wrote. I have 9 pins available on the BS2p40.
>
> Thanks in advance for any direction you can provide.
>
> Kind Regards,
> Eric