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Isolated Dual RS-232/Current-Loop Card


Ordering Information


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The PCL-741 provides two isolated RS-232 or current-loop serial ports. You can configure each port individually to RS-232 or current-loop using on-board jumpers.

The card has two 16C550 UARTs with on-chip 16-byte FIFO buffers. The UARTs buffer data into 16-byte packets before putting it on the bus. This drastically reduces CPU load and avoids data loss when the system is busy and cannot process the interrupt quickly. These FIFO buffers make the PCL-741 especially suitable for high speed serial I/O under Windows.

On-board optical isolators protect your PC and equipment against damage from ground loops, increasing system reliability in harsh environments.

The PCL-741 comes with the PC-ComLIB communication software package. The package consists of a configurable DOS driver, a programming library that supports most common languages (such as C, Pascal, Visual Basic, assembly and Clipper) and DataScope. DataScope is a data viewer and terminal emulator with self-diagnostic utilities for easy troubleshooting and debugging.


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  • PLC monitoring and control
  • Serial communication in harsh environments
  • Data entry terminals
  • Remote data acquisition and control
  • Instrument controller, distributed control systems
  • Interface to modem, bar code reader, scale, plotter feed, and serial links for PCs and instruments


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  • Two independent RS-232 or current-loop serial ports
  • Each port is individually configurable to RS-232 or current-loop (jumper selectable)
  • 16C550 UARTs with on-chip 16-byte FIFO
  • Transmission speed up to 56 Kbps
  • Provides 500 VDC isolation protection
  • Fully isolated ground and signal lines
  • Wide IRQ selection: 3, 4, 5, 7, 9, 10, 11, 12 or 15
  • Complete RS-232 modem control signals
  • Supports COM1, COM2, COM3, or COM4
  • PC-ComLIB software included


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  • Number of ports: 2
  • Protocol: RS-232 or current-loop (20 mA)
  • UART: 2 x 16C550 with 16-byte FIFO
  • I/O address: From 200H to 3F8H
  • IRQ: 3, 4, 5, 7, 9, 10, 11, 12 or 15
  • Data bits: 5, 6, 7, 8
  • Stop bits: 1, 1.5, 2
  • Parity: Even, odd or none
  • Power isolation: 500 VDC
  • Signal isolation: 2500 Vac
  • Power consumption: 5 V@300 mA typical, 1.1 A max.
  • Connectors: Dual DB-9 male
  • Operating temperature: 32 to 122 degF (0 to 50 degC)
  • Dimensions: 7.3" x 3.9" (185 mm x 100 mm)
  • Shipping weight: 1.3 lb. (0.6 Kg)


Ordering Information

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Isolated dual-port RS-232/current-loop interface card. Includes PC-ComLIB software.
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1280
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027