The NI USB-485/4 is a 4-port RS-485 serial interface that connects multiple instruments and sensors to a computer via USB. Each port features independent DB9 connectors and onboard switchable termination resistors to ensure signal integrity in multipoint configurations. The device supports data rates up to 3 Mbps with user-configurable transmit and receive FIFO buffers, automatic data direction control, and wide common-mode voltage tolerance to accommodate ground potential differences across distributed systems.
Technical Specifications
Serial Interface
• Number of Ports: 4
• Serial Standard: RS-485
• Maximum Data Rate: 3 Mbps
• Automatic Data Direction Control: Supported
• Onboard Termination: Switchable 120 Ohm resistors per port
• FIFO Buffers: User-configurable transmit and receive
USB Interface
• Connector: 1 × USB Type-A
• Standard: USB 2.0 High-Speed (480 Mbps)
• Power: Bus-powered
Electrical & Environmental
• Operating Temperature: −20 °C to 70 °C
• Storage Temperature: −40 °C to 85 °C
• Humidity: 5% to 95% non-condensing
• RS-485 Noise Immunity: Meets RS-485 input voltage tolerance standards
Physical
• Serial Connectors: 4 × DB9 male
• Enclosure: Metal or robust plastic construction
– Key Features
• Automatic RS-485 data direction control eliminates external signal management
• Multipoint communication capability for distributed sensor networks and daisy-chained instruments
• Wide common-mode voltage range compensates for ground potential differences in industrial environments
• Configurable FIFO buffers optimize data throughput for varied communication patterns
• Bus-powered operation requires no external power supply
– Typical Applications
• Industrial automation and process control
• Laboratory instrument integration and data acquisition
• Embedded systems requiring serial device connectivity
• Multi-device sensor networks over RS-485 networks
– Compatibility & Integration
• Operating Systems: Windows, macOS, Linux
• Software APIs: NI-Serial drivers, NI-VISA
• Compatible with standard serial communication libraries
