B&B Electronics CL33 RS-232 to Current Loop Converter

The B&B Electronics CL33 is a passive RS-232 to 20mA current loop converter designed for industrial serial communications. It enables seamless interfacing between modern RS-232 serial devices and legacy equipment that uses 20mA current loop signaling, a protocol commonly found in older industrial controllers, printers, and instrumentation.

Key Features:

• Converts RS-232 signals to and from 20mA current loop (active or passive loop configurations)
• Passive design — draws power directly from the RS-232 signal lines, no external power supply required
• Compact, rugged form factor suitable for industrial environments
• Compatible with standard DB-25 serial port interfaces
• Supports full-duplex communication
• No drivers or software required — transparent, plug-and-play installation

The CL33 is an ideal solution for engineers and technicians needing to maintain or integrate legacy serial equipment into modern systems. Its passive, self-powered design makes it easy to deploy without additional power infrastructure.