RS232 to RS422/RS485 Optically Isolated Serial Adapter / Converter CS-428/9AT-ISO2

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  • Regular price $89.00
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The SystemBase CS-428/9AT-ISO2 converts RS232 signals to RS422 or RS485 with optical isolation protection. It is a fast and efficient solution to overcome the distance limitations of RS232 or for connecting to industrial devices with an RS422 or RS485 interface.

No additional software is required for operation. With an easily accessible DIP switch, you can configure the interface for RS422 or RS485. The CS-428/9AT-ISO2 is fully compatible with the serial COM port on your PC.


  • 3KV Optical Isolation Protection
  • Maximum Communication Speed: 921.6Kbps
  • Industrial Grade Temperature: -40~85°C (IEC 60068-2-30/33)
  • Fully compatible with the serial COM port in the PC
  • External power not required (When DTR signal line is enabled)
  • Hardware-based Auto Toggling
  • RS422/RS485 mode, Termination, and Echo mode selectable by external switches
  • Max. 10 Devices Connectable for RS422 Multi-Drop Mode
  • Max. 10 Devices Connectable for RS485 Mode
  • Power: 9~12V, 500mA

Opto Isolation

The CS-428/9AT-ISO2 Opto-Isolation protects up to DC 2.5kV between the RS232 and RS422, RS485 sides. Opto-Isolation perfectly isolates the two endpoints so devices are protected from unfavorable electrical conditions such as ground potential differences, lightning, and line interference. This results in more stable and reliable communications.

SystemBase CS-428/9AT-ISO2 Optical Isolation Schematic

Auto RTS Control (Auto Toggling)

The CS-428/9AT-PRO2 has a built-in hardware feature that performs automatic toggling to prevent devices from sending data simultaneously. This operation is crucial when multiple devices are connected to prevent electrical collisions that lead to errors and unstable communications.

CS-428/9AT-ISO2 Specifications:


  • Maximum Speed: 921.6 Kbps
  • Maximum Distance: 1.2 Km. 24AWG twisted pair cable
  • Connectors:
    • RS232: DE-09S (DB9 Female)
    • RS422/RS485: Terminal Block 5 Pins
  • Signal Lines:
    • RS232: TXD, RXD, RTS, DTR, GND
    • RS422: TXD+, TXD-, RXD+, RXD-
    • RS485: TRXD+, TRXD-
  • RS422 Mode: Point to Point, Multi-Drop
  • RS485 Mode: Echo, Non-Echo
  • Slide Switch: RS422/RS485 selectable


  • Dimensions (W x L x H): 37 x 74 x 19 mm (1.45 x 2.92 x 0.75 inches)
  • Weight: 35g / 1.23oz

Operating Environment

  • Operating Temperature: -40~+85 C
  • Storing Temperature: -40~+85 C
  • Humidity: 5~95% Non-Condensing


  • Certificates: CE, KC

Package Includes:

1X CS-428/9AT-ISO2,
Download Guide, Warranty Policy

Additional Resources:

CS-428/9AT-ISO2 Manual, Utilities and Specifications Downloads (SystemBase Website)