Browse Prior Art Database

Modified Parallel Card to Suport Autodial (V25) Interface

IP.com Disclosure Number: IPCOM000111802D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Ryle, JJ: AUTHOR

Abstract

A parallel card may be modified to support V25 auto dial out of a PC by converting the input/output connector of the parallel card to the RS366 format and at the same time converting the TTL voltages to/from the connector to support the EIA voltages necessary to support the V25 dial. No change was made to the basic architecture of the parallel port: V25 parallel port auto dial architecture was supported by changing the voltages to the connector and coding the parallel card in 'C'.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Modified Parallel Card to Suport Autodial (V25) Interface

      A parallel card may be modified to support V25 auto dial out of
a PC by converting the input/output connector of the parallel card to
the RS366 format and at the same time converting the TTL voltages
to/from the connector to support the EIA voltages necessary to
support the V25 dial.  No change was made to the basic architecture
of the parallel port: V25 parallel port auto dial architecture was
supported by changing the voltages to the connector and coding the
parallel card in 'C'.

      The same technique can be used on the PS2* Micro Channel* card
using the Maxium (max232 chip) or the SN75150/75154 chip for
converting the TTL to EIA voltages, and vice-versa -- or, for that
matter, on the RISC System/6000, since the same parallel port is
used.

      The approach avoids a replacement of a modem/ACU and allows us
to transport protocols, such as Bisync (BSC), over SNA networks with
existing equipment.

The steps to modify the parallel card are:

    -   Convert the output lines from TTL to EIA voltages.

    -   Convert the input lines from EIA to TTL voltages.

    -   Configure connector to RS366 configuration.

The result is shown in the Figure.

The following describes the logic flow of the program used:

    -   Insure Modem is powered on and has Data Terminal Ready (DTR)
        raised.

    -   Check PWI/SLCT line of auto call unit to insure it is powered
        on.  [Inport instruction address 279 bit mask 10.]

    -   Check DLO/BUSY line of auto call unit to insure it is not in
        use.  [Inport instruction address 279 bit mask 80.]

    -   Get phone number from data base.

    -   Request dial to auto call unit by raising Call Request
        (CRQ/INIT).  [Outport instruction address 27A bit mask 04.]

    -   Check PND/ACK line of auto call unit to insure it came up
        which...