Host Interface

Host (PC or Android) connection to the RS485 bus can be achieved by an RS485 to USB converter. As an example, the RS485-USB converter from FTDIchip (FTDIchip Products USBRS485) was used for development by the author. Another possible candidate is the Sparkfun BOB-09822 breakout board. However, these converters do not provide host-based collision detection and have only a limited capability of host based collision avoidance.

A simple RS485-USB converter that provides collision detection and collision avoidance, can be made from an Arduino/Micro and an RS485 transceiver chip (See Figure1.jpg and Figure2.jpg on Hardware Connection ). The software to run on the Micro is provided in the example sketch RS485_USB (see RS485_USB ).

Various applications exist to communicate with the RS485 nodes on the bus. For simple command responds testing, a terminal emulator such as Putty (www.putty.org) or FTDI UART terminal will do. More complex applications must be developed explicitly. (In a future post, the development of an Android specific application will be published.