RS232 serial port line color definition is also different, each manufacturer's 

definition is slightly different.

Generally defined by color:

1 Black 2 Brown 3 red 4 Orange 

5 yellow 6 green 7 blue 8 purple 9 White

RS232 serial port connection method: direct connection

and cross connection

In general, RS232 serial line is required for the connection and communication 

between equipment and computer.

And the connection and communication between the device and the device,

Itwill use the cross line of RS232 serial port line. When users choose,

According 

to the actual situation of connection between two equipment,

Choose different RS232 serial port lines