Black Box Corporation IC820A Async RS232 to RS422/485 Media Converter

Async RS232 to RS422/485 Converter

The Black Box IC820A converts asynchronous RS232 signals to RS422 or RS485 standards for industrial and commercial data networks. It connects a DB9 female port to a terminal block and operates without custom handshaking code. The unit draws power from RS232 handshake lines or an optional external supply. Installers use it to extend legacy serial links over longer copper runs.

115 kbps or 4000 ft maximum reach

The converter transmits data at up to 115 kbps or spans distances up to 4000 ft, and this single limit decides whether the link meets the application. It supports point-to-point or multi-drop topologies with up to 32 RS485 devices on one bus. Four DIP switches select 2-wire half-duplex, 4-wire half-duplex or 4-wire full-duplex modes. No external jumpers are required for mode changes.

Sustained multi-drop operation

Under continuous load the RS485 driver enables automatically during each spacing state on the RS232 side, preventing bus contention without software intervention. The hardware handles 2-wire half-duplex or 4-wire full-duplex traffic indefinitely at the rated speed. Bridging switches keep the configuration stable in permanent installations. External 12 VDC power is only needed when handshake lines cannot supply enough current.