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Model: PCI20U
Manufacturer: Contemporary controls
PCI Bus Compatible ARCNET Network Interface Module
Product Status: Active - Active products are produced on a regular manufacturing schedule and are actively supported products. Active products are not necessarily in stock in the USA. Lead time to ship date for Active products is typically stock to 15 business days ARO.

Stock Status: Call

Since most PC motherboards have migrated from the +5 PCI Bus to the +3.3 V PCI bus, universal voltage PCI NIMs are required such as the PCI20U series of ARCNET network interface modules (NIMs). The PCI20U series links PCI and PCI-X bus compatible computers with the ARCNET local area network (LAN). In addition, the PCI20U series supports the PCI Add-in Card specification. Both standard height and half-height brackets are provided.

The PCI bus allows for jumperless configuration and Plug and Play operation (PnP). The module operates with either an NDIS driver or with a null stack driver in a Windows environment. DOS drivers will operate when used with our enabler software. Since the PCI20U is a universal voltage PCI card it can be used in either a PCI-X slot or a conventional PCI slot. PCI-X is an enhancement to the original PCI Local Bus Specification enabling devices to operate at speeds up to 133 MHz. If a PCI20U is installed into a bus capable of PCI-X operation, the clock remains at the 33 MHz frequency restricting all other devices on that bus to using the conventional PCI protocol.

The PCI20U incorporates the COM20022 ARCNET controller chip with enhanced features over the earlier generation ARCNET chips. New features include command chaining, sequential access to internal LAN, duplicate node ID detection and variable data rates up to 10 Mbps. Bus contention problems are minimized since the module's interrupt level and I/O base address are assigned through Plug and Play (PnP). There is no requirement for wait-state arbitration.

This device exploits the new features of the COM20022. This includes 10 Mbps communications utilizing the various EIA-485 transceiver options. This includes DC-coupled and AC-coupled (transformer) EIA-485 variants. Conventional 2.5 Mbps dipulse signaling is also supported.

Each PCI20U module has two LEDs on the board for monitoring network operation and bus access to the module. It is equipped with an 8-position, general purpose DIP switch which could be used to reassign the ARCNET node address without removing the module. Ultimately, the node address is configured via software so the DIP switch can be used for user-defined functions.


  • Interfaces ARCNET with PCI and PCI-X bus computers
  • Utilizes COM20022 ARCNET controller
  • Enhanced software capabilities over earlier generation ARCNET controllers
  • Node address switch selects one of 255 possible station addresses
  • Automatic configuration of I/O and interrupt
  • High-speed I/O access to the COM20022
  • Supports coaxial and twisted-pair cabling including EIA-485
  • Variable data rates up to 10 Mbps utilizing the various EIA-485 transceiver options
  • Suitable with all Contemporary Controls' MOD HUB and AI Series active hubs
Contemporary controls PCI20U-4000
Contemporary controls PCI20U-TB5
20022 PCI twisted-pair bus NIM
Contemporary controls PCI20U-CXS
20022 PCI coaxial star NIM
Contemporary controls PCI20U-CXB
20022 PCI coaxial bus NIM
Contemporary controls PCI20U-485X
20022 PCI AC-coupled EIA-485 (non-backplane) NIM
Contemporary controls PCI20U-485D
20022 PCI DC-coupled EIA-485 (non-backplane) NIM
Contemporary controls PCI20U-485
20022 PCI DC-coupled EIA-485 NIM (backplane invoked by software)