Description
Product Introduction & Engineering Value
The PCI20U-CXB is aimed at a very specific legacy-network problem: keeping an existing ARCNET installation connected to newer PCI or PCI-X computers. Unlike a generic Ethernet adapter, this card preserves the ARCNET physical layer and network architecture already used by the equipment.
For maintenance teams supporting older industrial computers, test systems, and automation equipment, that distinction matters. The PCI20U series supports both 3.3 V and older 5 V PCI systems, making the PCI20U a direct replacement family for the earlier PCI20 generation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Contemporary Controls |
| Model | PCI20U-CXB |
| Product Family | PCI20U |
| Network | ARCNET |
| ARCNET Controller | COM20022 |
| Network Topology | Coaxial bus |
| Data Rate | 2.5 Mbps |
| Connector | BNC |
| Recommended Cable | RG-62/u coaxial |
| Maximum Bus Segment | 1,000 ft / 305 m |
| Maximum Nodes per Segment | 8 |
| PCI I/O Mapping | 16 bytes |
| Interrupt | PCI INTA |
| Operating Temperature | 0°C to +60°C |
| Storage Temperature | −40°C to +85°C |
| Dimensions | Approximately 2.50 × 4.72 in. |
| Compliance | CE Mark; FCC/CFR Part 15 Class A |
Contemporary Controls specifies the -CXB version specifically for coaxial-bus ARCNET. The published data sheet lists a 2.5 Mbps data rate, RG-62/u cable, BNC connection, up to 305 m segment length, and up to eight nodes per segment.
Field Application & the “Trench” Experience
A machine builder had an older diagnostic workstation connected to an ARCNET network controlling several pieces of production equipment. The workstation computer was replaced because its original motherboard was no longer serviceable. The problem was immediate: the replacement PC had a PCI/PCI-X expansion architecture, but the production network still depended on coaxial ARCNET.
Rather than replacing the field network, the engineering team installed a PCI20U-CXB and retained the existing RG-62/u cabling and BNC network topology. After installing the appropriate driver and verifying the ARCNET node configuration, the workstation was brought back into the existing network.
The important detail was physical-layer compatibility. A PCI Ethernet card would not solve this problem.
Niche application scenarios
- Legacy ARCNET-connected industrial diagnostic computers
- Factory automation workstations using coaxial ARCNET
- Automated test equipment with existing ARCNET field networks
- OEM machinery where the ARCNET network cannot be economically replaced
- Industrial PC upgrades from older PCI hardware to newer PCI/PCI-X systems
Transparency SOP: QA & Testing
A PCI network card should be tested at both the computer interface and the ARCNET network interface.
1. Hardware inspection
- Confirm the PCI20U-CXB model marking.
- Inspect the PCB and BNC connector.
- Check the PCI edge connector for oxidation or mechanical damage.
- Verify the card has the expected hardware configuration.
2. Host-side test
Install the card in a compatible PCI or PCI-X computer and verify that the operating system detects the hardware and assigns the required I/O resources and interrupt.
The PCI20U requires 16 bytes of I/O space and supports PCI INTA.
3. ARCNET test
Connect the card to a known-good ARCNET coaxial segment and verify:
- Node recognition
- Network activity
- Data transmission
- Data reception
- Correct node address
New Surplus units should be checked for storage condition and OEM identification. Refurbished units should undergo both PCI host detection and ARCNET communication testing.
PCI20U-CXB
PCI20U-CXB
The Veteran’s Tech Trap Guide
⚠️ Trap 1: Confusing -CXB with -CXS
These suffixes are not cosmetic.
PCI20U-CXB is intended for a coaxial bus topology, while -CXS is intended for a coaxial star configuration using active hubs.
Do not substitute one for the other without checking the network architecture.
⚠️ Trap 2: Forgetting ARCNET termination
The -CXB is a bus topology interface. Contemporary Controls specifies passive termination at both ends of a bus segment. The published installation documentation specifies BNC-style 93-ohm termination and a maximum 305 m segment length.
PRO TIP: If a replacement card suddenly produces network errors, inspect the physical segment before blaming the PCI card.
⚠️ Trap 3: Assuming every PCI slot is equivalent
The PCI20U was designed for PCI and PCI-X computers and supports universal voltage operation. However, the host computer still needs an appropriate PCI expansion slot and compatible operating-system driver environment.
Dynamic FAQ
Q1. What is the Contemporary Controls PCI20U-CXB?
It is a PCI/PCI-X ARCNET network interface module designed for 2.5 Mbps coaxial-bus ARCNET networks.
Q2. What cable does the PCI20U-CXB use?
The -CXB version uses RG-62/u coaxial cable with BNC connectors.
Q3. What is the maximum ARCNET segment length?
The published specification gives a maximum coaxial-bus segment length of 1,000 ft (305 m), with up to eight nodes per segment.
Q4. Can PCI20U-CXB replace the older PCI20-CXB?
Yes. Contemporary Controls describes the PCI20U as a drop-in replacement for the PCI20, adding universal-voltage PCI compatibility for newer 3.3 V systems.
Q5. Is PCI20U-CXB compatible with PCI-X computers?
Yes. The PCI20U series interfaces with both PCI and PCI-X bus computers. When installed in a PCI-X-capable bus, the card operates at the conventional PCI 33 MHz clock rather than taking advantage of higher PCI-X bus speeds.
Q6. Are New Surplus and refurbished PCI20U-CXB units available?
Yes. Current industrial spare-part channels list the PCI20U-CXB in New Product, Never Used, and Refurbished condition categories. For a critical spare, request confirmation of the exact suffix, hardware condition, functional test procedure, and warranty coverage.
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