Hello friends,

In an 8052 based data logger, I have used a V23 modem chip. The data logger reports to a PC which has a standard modem supporting V23 protocol.

V23 connect procedure says that originating modem will connect at 75 BPS and receiving modem will connect at 1200 BPS. There is no other choice (Remember, I made one modem, not both)

So tha data logger will transmit at 75 BPS, which is slow.

V23 protocol has some variations. One of them is PAVI or V23 Reversing or V23 Turnaround. In simple words, both modems connect as I stated above. When connection is established, the originating modem sends request to answering modem to swap the speeds. Thus originating modem transmits at 1200 BPS and answering modem becomes 75 BPS.
For those who wish to know more about V23 PAVI operations,

V23 Reversing

But for reversing to occur, both modems should support it. I can implement it in my data logger modem, but not on ready made PC modem.

Now my questions are:

1) Does any body know of a commercial PC modem which supports V23 Reversing? (At least I couldn't find one)
2) Can any body advice how to do it in any commercial modem i.e. US robotics or Motorola ?
3) Would above be possible or I have to make my own modem for PC as well?


Any help/advice in this regard will be appreciated.

Regards

IA