The hardware is:
1. PC connect to Modem using COM1, modem connect to
2. The other side is a Machine (control by AT89c2051 microCPU) connect to modem using COM Port, the modem connect to telephone line.
I want to do this:
The PC dial up to the Machine, and then communicate with
the machine using COM port.
The PC and Machine only use three signal lines (TX, RX,GND) to communicate with the modem.
I can communicate with the machine throght COM by RS-232
Direct connect line.
MY PC (WIN98,VB6, using MSCOMM control)
Can anybody tell me how to communicate with the machine