Contemporary Controls PCI20U-CXB Universal PCI ARCNET NIM

Description

Key Technical Specifications

Product Introduction

The PCI20U-CXB is Contemporary Controls’ universal-voltage ARCNET network interface module, built around the COM20022 controller chip specifically to solve a hardware transition problem: when the PCI standard moved to +3.3V-only slots on newer motherboards, the original +5V-only PCI20 could no longer be counted on to fit every system. The PCI20U line was designed as a direct drop-in replacement that works in both +3.3V and +5V PCI slots without any user-side migration work, and it remains functional even on PCI-X capable buses, running at the conventional 33 MHz clock.

The -CXB configuration specifically supports coaxial bus topology, which is the common configuration in GE Mark V Speedtronic turbine control HMI installations upgrading from ISA-bus ARCNET cards. Note that this variant is fixed at 2.5 Mbps — if your application needs the series’ higher 5 or 10 Mbps rates, that’s only available on the EIA-485 variants (-485, -485X, -4000) in this same family, not on -CXB, -CXS, or -TB5.

PCI20U-CXB

PCI20U-CXB

Installation & Configuration Guide

Stage 1: Pre-Installation Preparation (~15 min)

⚠️ Safety First: Notify operations of the HMI downtime window. This card sits in the operator interface computer, not the turbine control cabinet itself — confirm no critical monitoring function depends solely on this HMI before taking it offline. Power down and unplug the PC before opening the case.

Tools Required: ESD wrist strap, PH1/PH2 screwdriver, digital multimeter, smartphone for reference photos.

Data Backup: If replacing an older PCI20 (+5V) card or an ISA-bus card, verify your driver stack (TCI, or equivalent NDIS/null-stack driver) explicitly supports the PCI20U series before proceeding — driver compatibility, not the card’s own Plug-and-Play behavior, is the most common point of failure on this kind of upgrade.

Stage 2: Removing the Old Card (~5 min)

1. Remove the PC case cover.
2. Label and disconnect the coaxial ARCNET cable from the old card.
3. Release the card’s rear-bracket screw and pull the card straight out of the PCI slot.
4. Inspect the now-empty slot for dust or debris, and confirm whether the target slot is +3.3V or +5V — the PCI20U is designed to work in either, so this is a compatibility check, not a blocker.

Stage 3: Installing the New Module (~15 min)

1. ESD prep. Seat the PCI20U-CXB in an available PCI slot and secure the rear bracket screw — use the half-height bracket if your chassis requires a low-profile card.
2. Reconnect the coaxial ARCNET cable to the new card.
3. Close the PC case and reconnect power.
4. Boot the PC and allow Plug-and-Play to assign the I/O base address and interrupt automatically.

Self-Checklist: [ ] Card seated and bracket secured [ ] Coax cable reconnected [ ] Driver stack confirmed compatible with PCI20U series [ ] DIP switch/node address setting confirmed

Stage 4: Power-On & Testing (~15 min)

Pre-Power Check: Confirm the coaxial cable is properly terminated per your network topology before applying power.

1. Boot the PC and confirm the card is recognized with an assigned I/O base address and IRQ.
2. Confirm the two onboard LEDs indicate network operation and bus access as expected.
3. Verify node addressing through the application software (node address on this generation is ultimately software-configured, not solely DIP-switch driven).
4. Confirm communication with the rest of the ARCNET network before returning the HMI to production.

⚠️ Troubleshooting Note: If the card isn’t recognized correctly, double-check that your driver version explicitly supports the series — the universal-voltage hardware compatibility doesn’t guarantee driver-level compatibility if you’re running software written against the original PCI20/COM20020 combination.

Frequently Asked Questions (FAQ)

Can the -CXB be hot-swapped under power?
No. It’s a PCI-bus card — power down and unplug the host PC before installing or removing it.

Is the -CXB obsolete, and is “new” stock genuinely new?
It’s a mature product in a legacy technology category — Contemporary Controls has since introduced the PCI Express-based PCI20EX as the modern-motherboard successor for new installations, though ARCNET itself remains actively supported by the company because of installed-base demand in systems like GE Mark V. Expect current supply to be a mix of remaining factory stock and secondary-market inventory; state which applies to your specific unit.

Is this a direct replacement for the original +5V PCI20 card?
Yes — that’s the entire design intent of the “U” designation. The is a drop-in replacement for the +5V-only PCI20, engineered specifically so it works in both +3.3V and +5V PCI slots without additional migration work.

What’s the difference between the -CXB, -CXS, and -485 variants in this series?
-CXB supports coaxial bus topology (typically no hub needed); -CXS supports coaxial star topology (typically requires an external hub); -TB5 supports twisted-pair. The -485/-485X/-485D/-4000 variants use EIA-485 transceivers and support significantly higher data rates (up to 10 Mbps) than the -CXB/-CXS/-TB5 models, which are fixed at 2.5 Mbps. These aren’t interchangeable without matching your existing network’s physical topology.

Will I lose my ARCNET node configuration when I swap the card?
Node addressing on the generation is ultimately set via application software rather than purely hardware DIP switches, so confirm your node address configuration in the driver/application software after installation rather than assuming the physical DIP switch setting alone carries it over.

Why is your price lower than other “new” listings for this model?
On a mature product like this, price differences generally track inventory age and testing depth rather than product quality — state plainly whether the unit is unused older factory stock or tested/rebuilt secondary-market inventory before quoting a customer.