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OBSOLETE - Will only manufacture on

receipt of a large order


Bus Expansion Kit


ACCES' model PTRC-AT Bus Expansion Kit allows you to expand your personal computer system without timing or noise problems. It provides software-transparent, active, 16-bit Bus extension between the computer and a separate expansion chassis, operator-less station, or cell controller. This bus expansion kit uses active circuits and high-speed logic to minimize propagation delays. Also, multilayer printed circuit boards are used and the design is optimized for proper impedance match to avoid spikes and ringing.

The kit consists of two cards and an interconnect cable. The expansion transmitter card (PT3-AT) plugs into the host computer and the expansion receiver card (PR3-AT) plugs into an expansion chassis backplane. All that is required in the expansion chassis is a properly terminated backplane (up to 20 slots) and an appropriate size power supply. Power should be applied near-simultaneously to both the computer and the expansion chassis. This is easily accomplished by connecting both units to the same power strip. A one-meter long, shielded cable interconnects the two cards and mates with connectors on the card mounting brackets.


Computer resources such as SVGA cards or disk controllers can be installed in the expansion chassis but there are two exceptions:
  • Some Super-VGA graphic cards cannot be installed in the expansion chassis because they use the Compressed Write Timing signal and propagation time though the two backplanes plus the cable is too long. Thus, those Super-VGA cards must be installed in the computer chassis.
  • Bus Mastering from the expansion chassis is not supported. Thus, in any application where a "smart" device takes over the CPU bus, this device must be installed in the computer chassis.

Model PTRC-AT is fully compatible with Plug-and-Play (PnP) cards. Further, power at the expansion chassis can be cycled off/on. This provides means to test multiple cards without removing power from the computer and, thus, avoid the time required by the computer to boot up. However, cards that configure the computer's BIOS at power-up ("power-on system configuration") require a reboot when their power is cycled.

There are no restrictions on I/O bus address range and you do not need to set any configuration switches or run any initializing software. The PT3-AT card can be configured by a jumper to assert one or two wait states in hardware. However, the majority of personal computers will work acceptably without the wait state when communicating with an expansion chassis. If speed of communication is important in your application, place the wait-state jumper in the lower (inactive) position and determine empirically if that works in your application.

Operation is not CPU related, and is therefore compatible with 80286 through Pentium computers. ISA bus speed is specified at 8.33 MHz, but operation at faster bus rates may work in your specific application.

Cards types that can be installed in the expansion chassis include (but are not limited to):

  • Analog and Digital data acquisition and control cards
  • Video cards (except some Super VGA cards)
  • Multi-port serial communication cards
  • Network cards (non bus-mastering)
  • DSP cards (non-bus mastering)
  • Tape back-up controllers
  • Modem and FAX cards
  • Video capture cards
  • Sound cards



  • 16-bit AT (286/386/486) and Pentium and EISA-Bus computers.

    Wait State:

  • Jumper selectable for either 0, 1, or 2 wait states asserted in hardware.

    Interconnect Cable:

  • Shielded, standard length is one meter. Two meter cable available as an option.


  • PT3-AT: 6.44" (163.6 mm) long x 3.9" (99 mm) (seated height).
  • PR3-AT: 6.73" (171.0 mm) long x 3.9" (99 mm) (seated height).

    Power Required

  • PT3-AT: 5VDC @ 1.3A typical.
  • PR3-AT: 5VDC @ 1.4A typical.


  • Operating Temperature Range: 0° to 60°C.
  • Storage Temperature Range: -50° to 120°C.
  • Relative Humidity: 0 to 90% RH, non-condensing.

    Regulatory Compliance

    • This product is in full compliance with CE requirements.


Part Number Price(USD)
PTRC-AT please call
PTRC-AT6 please call


Acquisition Control Communications Engineering / Systems

USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
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