Industrial Passive RS232 To RS485 Bi-Directional Converter

The Valtoris Passive RS232 to RS485 Adapter provides unpowered, bidirectional serial conversion for industrial networks. It harvests operating power directly from the RS232 port, supporting high-speed transmission up to 230,400 bps. Features a flange-mountable terminal block and built-in TVS surge protection for reliable telemetry in space-constrained control panels.

Part No. RS232 TO RS485
sku : IoT-IC102
INSTANT QUOTE

Unpowered Serial Conversion

This Passive RS232 to RS485 Adapter requires zero external power. It extracts operating power directly from the RS232 TXD, DTR, and RTS pins to convert single-ended RS232 signals into balanced, half-duplex RS485 data.

Passive RS232 to RS485 Adapter Overview
Port-Powered RS232 Conversion capability

High-Speed & Broad Compatibility

Achieves error-free communication at baud rates up to 230,400 bps via an advanced internal charge pump. Highly compatible with standard TTL, PL2303 USB cables, and legacy 3-wire RS232 devices (RXD/TXD/GND) lacking flow control pins.

Bidirectional RS232 to RS485 Transmission Architecture

Dimensions & Mounting

Equipped with a standard DB9 female connector (RS232) and a 3-pin terminal block with flange mounts (RS485) for secure, vibration-resistant panel installation.

Outline Mechanical Dimensions Schematic

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Hardware & Interfaces
Electrical StandardEIA/TIA RS232C / RS485
RS232 InterfaceDB9 Female (Hole-type)
RS485 Interface3-Pin Terminal Block with Flange Mount
Communication Parameters
Operation ModeAsynchronous Half-Duplex
Transmission Rate300 ~ 230400 bps
Max Distance (RS232)15 Meters
Max Distance (RS485)1200 Meters
Signals & Environment
RS232 SignalsTXD, RXD, GND (RTS & CTS internal short-circuit)
RS485 Signals485A+, 485B-, GND
Operating Temp.-40°C to +85°C
Humidity Range5~95% RH
⚙️ Core Connectivity Advantages
✓ Port-Powered Operation: No dedicated external power supply is required. Power is efficiently harvested from standard RS-232 signal lines (TXD, DTR, RTS).
✓ High-Speed Communication: This unit is capable of transmitting data at speeds of up to 230400 bps (standard passive converters are limited to 57.6kbps).
✓ Universal Compatibility: Seamlessly compatible with various RS232 interfaces such as standard TTL, PL2303 USB-to-Serial cables, and 3-wire (RXD/TXD/GND) devices without flow control pins.
✓ Automatic Flow Control: Internal shorting of RTS and CTS pins automatically controls data direction turnaround without software intervention.
✓ Rugged Industrial Build: Features a fully enclosed, CE-certified chassis with built-in TVS surge protection for the RS485 lines and secure flange-mount terminals.

Frequently Asked Questions

Does this adapter require an external 9V or 12V power supply to operate?
No. It is a completely passive device. It features a built-in 4-channel charge pump circuit that intelligently “steals” electricity directly from the RS232 port’s TXD, DTR, and RTS pins, making it truly plug-and-play.
My legacy RS232 device only has 3 wires (RXD, TXD, GND) and no flow control pins. Will this still work?
Yes. In this case a standard converter will not work. Our adapter is designed to pull enough power from the TXD pin alone to work properly as long as your device is outputting standard RS232 TTL voltage levels.
Can it sustain high-speed communication at 115200 bps?
Absolutely. Standard passive converters often struggle above 57600bps due to weak power harvesting. This adapter’s advanced circuit design guarantees strong, error-free, long-duration communication at baud rates up to 230400 bps.
How does the adapter handle Modbus RTU data direction (Transmit/Receive switching)?
It features automatic flow control. The RS232 flow control pins (RTS and CTS) are internally short-circuited. The internal circuitry automatically senses data direction and manages the half-duplex RS485 line turnaround without requiring any software modifications on your host system.
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