Table of Contents
Advertisement
Print date: 02/04/2015
5. RS-232 Information
5.1 The RS-232 Standard
The RS-232 standard was introduced in 1962, it is now widely established. RS-232 is a slow speed,
short distance, single ended transmission system (i.e. only one wire per signal). Typical RS-232
maximum cable length is 50 feet.
5.2 9 Pin D Serial Port RS-232 Cables
To connect to the RS-232 Serial Port you will need a cable terminating in a 9 way female D
connector. It is sound practice to use cables with screws fitted that will allow you to fasten the cable
securely to the PC card.
In general, you will need to make up a "cross-over" cable to correctly interface the PC to the RS-232
port of another computer or device. Provided you have the pin outs and handshake requirements of
both sides of your RS-232 connection, the cross over cable becomes a matter of common sense. The
cross-over cable is simply to ensure that the right signals going out of one RS-232 port go into the
appropriate lines of the other RS-232 port.
5.3 Pin D serial port connection to another PC
Suppose we want to connect the Brainboxes Serial Port to the serial port of another PC. 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.
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.
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.
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.
Schematic and Actual presentations are shown below.
XC Range Product Manual
© Copyright Brainboxes Ltd
Page 24 of 38
V1.0
Advertisement
Table of Contents
