Introduction to the Serial Communication
CFW-11 | 6
1
INTRODUCTION TO THE SERIAL COMMUNICATION
In a serial interface, the data bits are sent sequentially through a communication channel, or busbar. Several
technologies use serial communication for data transfer, including the RS232 and RS485 interfaces.
The standards that specify the RS232 and RS485 interfaces, however, do specify neither the format nor the
character sequence for data transmission and reception. In this sense, besides the interface, it is also necessary
to identify the protocol used for the communication.
The BACnet MS/TP network defines the BACnet message exchange using the RS485 interface as the physical
layer.
The characteristics of the RS485 serial interfaces available in the CFW-11 frequency inverter, as well as the
BACnet protocol, will be presented next.
