RS-422 interface for PMC

The PMC CD-20 has been discontinued, and is no longer supported. The information on this page is provided for reference only.

  • Transfer rates up to 20 MB per second
  • 4 KByte FIFO
  • Implements a high speed DMA channel between an external device and PMC computers
  • RS-422 compatible driver/receivers
  • Customizable by a RAM based programmable gate array
  • Synchronous protocol
  • Clock timing from DMA interface, user device, or both
  • Device drivers for Linux and Windows
  • Single PMC slot
  • PMC version also available

The PMC CD-20 interface provides a high-speed 16-bit parallel DMA channel between an external device and a PMC/PCI bus computer. The device interface uses RS422 compatible driver/receivers connected to a RAM-based programmable gate array and 1 KByte FlFOs. The PMC CD-20 uses direct virtual memory access (DVMA) and asynchronous I/O to achieve transfer rates to or from memory of up to 20 MB per second. The hardware protocol is synchronous. That is, all data and control signals are sampled with a clock transmitted along with the data and control signals. This clock may be generated by the DMA interface or the user device or both. All signals are differential using RS422 specifications. The PMC CD-20 includes a versatile, straightforward protocol but optional customer-specific protocols may be developed.

The board complies with PMC form factor specifications and will fit in any PMC slot.

  • Telecom Receivers
  • Simulation
  • Imaging devices
  • Scanners
  • Plotters
  • Device Control
  • Research and development
  • General Purpose Data Acquisition

Device drivers for supported operating systems are included with the PMC CD-20. The drivers provide access to the PMC CD-20 through standard and asynchronous read and write system calls. Continuous transfers are implemented with asynchronous I/O.

The PMC CD-20 is provided with minimal Codes PROM for identification only. User Code PROMS MAY be developed for specific applications.


EDT provides several levels of customer support, from phone consultation to custom design of hardware, firmware, or software, at hourly rates. Technical support is also provided though the Technical Information section of this web site.


PMC Compliance


PCI Bus compliance

PCI 2.2

Device interface


Synchronous streaming


1 KB FIFO for input 1 KB FIFO for output


AMP 787190-8 high-density 80-pin (mates with AMP 749621-8, backshell 749196-2)*


Temperature: Operating, 10° to 40° C; non-operating, -20° to 60° C
Humidity: Operating, 20% to 80% noncondensing at 40° C; non-operating, 95% noncondensing at 40° C


Single standard PMC slot
Dimensions: 74mm x 152mm
Weight: 3.5 oz.


1.2A at 5 volts


Device drivers for Linux and Windows
Standard read/write system call support
Asynchronous I/O support for continuous transfers

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The PCI CD-20 has been discontinued and is no longer available. The PCI CDa usually can be used in its place. The information on this page is provided for use by existing customers; however, our ability to provide ongoing support is… Read more »