The HXSP-2118F USB To RS485 Converter is a heavy-duty, commercial-grade communication adapter engineered to bridge standard host computer USB ports directly to half-duplex, two-wire balanced differential RS-485 networks. Built with automatic I/O data flow direction control (zero-latency auto-transceiver switching), it eliminates the need for manual RTS/CTS handshake programming in software. Featuring high-grade transient voltage suppression (TVS) rated up to 600W per line and 15kV ESD protection, the HXSP-2118F is designed to withstand harsh industrial electrical noise, ground potential shifts, and lightning-induced surges across extended communication distances up to 1,200 meters (4,000 feet).

Specifications

• Model / Part Number: HXSP-2118F (Commercial / Industrial Grade USB-485)
• Interface Standards: Fully compliant with USB 2.0 / USB 1.1 and EIA/TIA RS-485 standards
• Host Interface: USB Type-A Male (Direct plug-in to PC / industrial IPC host port)
• Device / Field Interface: 2-Pin / 3-Pin Pluggable Screw Terminal Block (A+/D+, B-/D-, GND$)
• Transmission Mode: Asynchronous, Half-Duplex, Point-to-Multipoint, 2-Wire Differential
• Automatic Flow Control: Hardware Zero-Delay Automatic Send / Receive Direction Control (I/O Auto-Transceiver)
• Baud Rate / Data Speed: 300 bps to 115.2 kbps (Auto-detecting and self-adapting baud rate)
• Maximum Transmission Distance:
  • USB Side: Standard ≤ 5 Meters (16 Feet)
  • RS-485 Side: Up to 1,200 Meters (4,000 Feet) at 9600 bps; ~100 Meters at 115.2 kbps
• Multi-Drop Bus Capacity: Supports up to 32 standard RS-485 transceiver nodes on a single multi-drop bus
• Power Supply: Fully USB Bus-Powered (5V DC from host USB port; draws < 30>
• Surge & ESD Protection:
  • Transient Voltage Suppressor (TVS): 600W per line lightning/surge suppression
  • Electrostatic Discharge (ESD): ±15kV Human Body Model (HBM) air/contact discharge
• Operating System Compatibility: Windows 11 / 10 / 8.1 / 8 / 7 / Vista / XP, Linux, macOS, Android (Virtual COM Port)
• Transmission Media: Shielded Twisted Pair (STP / UTP, 24 AWG to 22 AWG) or dedicated 2-wire industrial serial bus
• Operating Ambient Temperature: -25°C to +70°C (-13°F to 158°F)
• Relative Humidity: 5% to 95% (Non-condensing)
• Dimensions: Approx. 70 mm × 18 mm × 14 mm (Compact dongle form factor)
• Net Weight: Approx. 25 g to 35 g

Pinout & Terminal Definition

• Terminal A+ (D+ / 485+): Non-Inverting RS-485 Differential Data Line (Active-High)
• Terminal B- (D- / 485-): Inverting RS-485 Differential Data Line (Active-Low)
• Terminal GND (PE / Ground): Signal Reference Ground / Shield Drain Connection

Features

• Zero-Latency Automatic Direction Switching: Internal hardware automatically detects data stream direction and toggles the RS-485 driver enable line in microsecond timings, ensuring complete compatibility with standard serial software and Modbus RTU/ASCII protocols without custom driver modifications.
• Robust 600W TVS & 15kV ESD Protection: High-speed clamping diodes suppress voltage spikes from lightning, motor back-EMF, and static electricity, protecting the host computer's USB subsystem.
• Direct USB Bus-Powered: Operates directly from the 5V USB bus without needing an external power supply or cumbersome DC wall adapters.
• Integrated Status Indicators: Features onboard LED indicators for Power (PWR), Data Transmit (TXD), and Data Receive (RXD) for instant visual troubleshooting.
• Plug-and-Play Virtual COM Port: Generates a standard COM port (e.g., COM3, COM4) on the host operating system, seamlessly interfacing with terminal emulators, SCADA software, LabVIEW, and PLC programming suites.

Common Applications

• Modbus RTU Industrial Networks: Polling data from energy meters, solar inverters, PLC controllers, variable frequency drives (VFDs), and remote RTU modules.
• Building Automation & HVAC: Interfacing chiller controllers, digital thermostats, environmental sensors, and building management systems (BMS).
• PTZ Surveillance Systems: Controlling pan-tilt-zoom security cameras over long distances using Pelco-D / Pelco-P telemetry protocols.
• Access Control & Time Attendance: Managing distributed RFID card readers, biometric turnstiles, smart locker systems, and parking gates.
• Factory SCADA & Data Acquisition: Connecting distributed sensors, industrial weighing scales, barcode scanners, and temperature monitoring arrays to central industrial PCs.

Usage Tips

• Polarity & Differential Matching (CRITICAL):
  • Always connect A+ to A+ (or D+) and B- to B- (or D-) across all devices on the bus.
  • Reversing the A+ and B- lines will invert the logic levels, causing communication framing errors, CRC failures, or no response from slave devices.
• Daisy-Chain Topology (No Star Wiring):
  • RS-485 requires a strict daisy-chain (linear bus) topology. Run a single continuous cable from the converter to the first device, then to the second, and so on.
  • Avoid star or tree branching, as long stubs cause severe transmission line reflections that corrupt data packets.
• 120Ω Termination Resistors: For long cable runs (>100 meters) or baud rates higher than 19.2 kbps, connect a 120Ω (1/4W) resistor across A+ and B- at the two physical ends of the bus (one at the HXSP-2118F and one at the furthest slave device) to absorb line reflections.
• Shielding & Common Ground: Always use Shielded Twisted Pair (STP) cable. Twist the A+ and B- wires together, and tie the outer foil/braided shield to the GND terminal at a single point to prevent ground loop currents while draining external electromagnetic interference.
• Driver Installation: Ensure the correct Virtual COM Port (VCP) driver (typically FTDI, CH340, or Prolific depending on the internal ASIC batch) is installed via Device Manager to ensure uninterrupted, low-latency transmission.