The RS485 interface supports higher data rate and distance compare to RS232. It supports distance of 10 meters for 30-35 Mbps and 1200 meters for the data rate of about 100 kbps. It is a balanced differential interface used mainly for multi drop configuration. Figure-1 depicts pin configurations of RS485 interface in a 9 pin DB9 connector.
This example sets the RS-485 transceiver control modes for a specified port and then performs basic serial communication in that transceiver mode. This example opens one VISA resource and configures one COM port. It sets the RS-485 transceiver mode and then performs a serial port read, a serial port write, or both based on the options (read or write) that the user selects on the front panel.
If both are selected, the VI will first write data, then read data, and finally close the VISA session that is opened to the port.Note: This example will only work with National Instruments RS-485 interfaces.To use this example in LabVIEW 6.1, please search for 'Serial Communication for LabVIEW 6.1'.