This application note describes how to use a Philips 16C UART to implement a simple RS-485 transmitter and receiver node.
The document describes an application using a Philips SC16C UART (e.g., SC16C554, SC16C554B, SC16C654, SC16C654B) to implement a simple RS‑485 transmitter/receiver node. It details the data frame format, control characters, and software structure required for half‑duplex communication over an ISA bus.
It also outlines software limitations such as lack of CRC error checking, limited control characters, and inability to handle other interrupt sources, and provides conclusions and suggestions for extending functionality. This manual is written in Chinese.
| Node address range | 0x07…0x7F |
|---|---|
| EOF character | 0x60 |
| ACK character | 0x61 |
A Philips SC16C UART such as the SC16C554, SC16C554B, SC16C654 or SC16C654B is used.
Address characters have the parity bit set to 1, while data characters have the parity bit set to 0.
The defined control characters are the address byte, EOF (0x60) and ACK (0x61).