CHAPTER 1
INTRODUCTION

The PCCOM RS422/RS485 adapter provides two asynchronous serial communication ports, which enables one computer via communication lines, or to link the computer and serial peripheral devices such as terminals, modems, serial printers, plotters, ... etc.

The PCCOM RS422/RS485 board can be installed in any IBM PC/XT, PC/AT, PC/386, or hardware compatible system. To accommodate a variety of operating systems seven jumpers permit maximum flexibility of congiguration. You may select which interrupt (IRQ2 - IRQ7), I/O address you desire.

The PCCOM RS422/RS485 adapter provides signal drivers and receivers, which can be set by software or hardware. Since the adapter support differential communication lines, it provides longer and more reliable communication quality than does RS232. The communication speed is up to 460K baud and the maximum transmission distance is up to 4000 ft.

Under the RS422 mode, RTS and CTS are used to provide communication flow control protocol. Under he RS485 mode, only transmission and receive signal are used, both drivers and receivers can be enabled or disabled by jumper setting or software. This means the RS485 provides a multi-point communication protocol.