AMX TXC16 Plus User Manual download pdf (Page 13)

DB9 to DB25 converter

The original pin layout for RS232 was developed for a 25 pins sub D connector. Since the IBM-AT, 9

pins connectors are commonly used. In mixed applications, a 9 to 25 pins converter can be used to

connect connectors of different sizes.

RS232 DB9 to DB25 converter

RS232 null modem cables

The easiest way to connect two PC's is using a null modem cable. The only problem is the large variety

of null-modem cables available. For simple connections, a three line cable connecting the signal ground

and receive and transmit lines is sufficient. Depending of the software used, some sort of handshaking

may however be necessary. Use the selection table

to find the right cable for each purpose. For a

Windows 95/98 Direct Cable Connection, the null modem cable with loop back handshaking is a good

choice.

Null modem cables with handshaking can be defined in numerous ways, with loopback handshaking to

each PC, or complete handshaking between the two systems. The most common cable types are shown

here.

Simple null modem without handshaking

No handshaking

How to use the handshaking lines in a null modem configuration? The simplest way is to don't use them

at all. In that situation, only the data lines and signal ground are cross connected in the communication

cable. All other pins have no connection. An example of such a cable without handshaking can be seen

in the figure below.

Compatibility issues

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AMX TXC16 Plus User Manual Page 13