9 Pin D Serial Port Connection To Another Pc - Brainboxes CC-357 User Manual

PCI VelocityRS232/422/485

9 Pin D Serial Port Connection To Another PC.

Suppose we want to connect the AT style 9 pin D Serial Port to the
serial port of another IBM PC. See Figure 4-3.
1) Connect the earth lines.
Line 5 of Serial Port 2 to lines 1 & 7 of the other PC.
This gives the two devices a common earth level.
2) Connect the Transmit and Receive lines together.
Line 3, TXD, Port 2 goes to line 3, RXD, of the other PC.
Line 2, RXD, Port 2 goes to line 2, TXD, of the other PC.
This allows each to receive the data transmitted by the other.
3) Connect the Port 2 DTR line, pin 4 to the other PC DCD, pin 8
and CTS, pin 5, lines.
Also, connect up the other PC DTR line, pin 20 to the Port
2 DCD, pin 1 and CTS, pin 8, lines.
This allows the receiving device to signal when it can no
longer accept data. The receiving device sets DTR false when
it is unable to receive any more data. The sending device reads
DTR on its CTS and DCD pins. It should stop sending when
CTS goes false.
4) Connect the Port 2 RTS line, pin 7, to the other PC DSR line,
pin 6. Also, connect the other PC RTS line, pin 4, to the Port 2
DSR line, pin 6.
This RTS line is used to let the other device know that it is
ready for data exchange.
Chapter 4 Page 66
RS232 Pinouts & Cabling