The Opto-22 AC37 is an ISA Bus high-speed serial processor module engineered for AT-class IBM-compatible computers. It delivers isolated RS-485 communication over twisted-pair cabling, supporting both half-duplex (2-wire) and full-duplex (4-wire) topologies at speeds up to 460,800 baud. The module emulates a standard IBM serial COM port with configurable 16,550 UART modes, enabling seamless integration with Opto 22 16-bit and 32-bit software and hardware. A 512-byte FIFO buffer prevents data loss during high-speed transfers, while 2,500 VAC optical and transformer isolation protects RS-485 lines from transient damage. Transmission distances reach 3,000 ft (914.4 m) at 115,200 baud. Installation requires a 16-bit ISA slot; four status LEDs (TX, RX, IRQ, Run) provide operational visibility. Jumper-configurable modes support character-by-character reception (Mode 0) or buffered block transfer (Mode 1), with additional jumper settings for host or redundant host operation on Opto 22 Remote I/O Bus networks.
Technical Specifications
• Bus Interface: 16-bit ISA slot
• Serial Protocol: RS-485 (half-duplex 2-wire or full-duplex 4-wire)
• UART Emulation: 16,550 compatible; modes 0 and 1 selectable via jumper
• Maximum Baud Rate: 460,800 baud
• Cable Distance: 3,000 ft (914.4 m) @ 115,200 baud
• Data Buffering: 512-byte FIFO (transmit and receive)
• Isolation: 2,500 VAC transient protection; optical and transformer isolation
• Power Consumption: 5 VDC @ 800 mA
• Operating Temperature: 0 °C to 60 °C (32 °F to 140 °F)
• Humidity Rating: 95% relative humidity, non-condensing
• Connector: Phoenix Contact MC 1,5/7-STF-3,81 (removable cable plug)
– Key Features
• Configurable half-duplex and full-duplex operation
• Mode selection for character or block transfer protocols
• Jumper-selectable host/redundant host roles
• Transmit, receive, IRQ, and run status indicators
• Common-mode voltage rejection via optional reference wire
• Grounded shield capability for noise immunity
– Compatibility & Integration
Designed for AT-class IBM-compatible computers (286, 386, 486). Compatible with all Opto 22 16-bit and 32-bit hardware and software. Supports Mistic I/O brick and controller networks. Terminating resistors required at both transmission line ends.
