Here's news of a new ARCNET card that will work in old and new PCs.
What's this? You've never heard of ARCNET?
ARCNET was once quite popular in office automation. Recently, it has re-invented itself into an embedded networking technology that's finding use in industrial control, building automation, transportation, robotics, and gaming systems.
Popular in Japan, with continuing popularity in America and Europe, ARCNET is even making inroads into China, especially at Chinese universities.
Like Ethernet, ARCNET is a data-link layer technology with no defined application layer. You write your own application layer to meet your needs.
Interestingly, many folks embedding ARCNET don't advertise the fact that ARCNET is being used. As such, ARCNET receives no name recognition, but nontheless it's frequently the network protocol of choice for OEMs and network implementers. Though it's hidden from users, over ten million ARCNET nodes have been implemented.
Deterministic Token Passing
Originally introduced at about the same time as probabilistic Ethernet, ARCNET uses a token-passing protocol where media access is determined by a station holding the token.
When a station receives the token, it can either initiate a transmission to another station or pass the token to its logical neighbor.
All stations are considered peers and no one station can consume all the bandwidth, since only one packet can be sent for each token pass.
This scheme avoids collisions and gives ARCNET its greatest advantage in realtime applications, as it's deterministic. You can therefore accurately predict the time it takes for a station to gain access to the network and send its message. This is important for control and robotic applications where timely responses or coordinated motion are needed.
Okay, so what't all this got to do with new and old PCs? Well, consider that the PCI standard requires that plug-in boards use a +3.3-V power source provided by a PC motherboard, making the +5-V power source obsolete.
In response, Contemporary Controls Systems (Downers Grove, Illinois) is rolling out a universal-voltage PCI ARCNET network interface module that's compatible with both new +3.3-V (PCI-X), and older 5-V computers.
A Drop-In PCI Replacement
The module, dubbed the Model PCI20U, is a drop-in replacement for the firm's earlier PCI20, a 5-V PCI card. "This removes any work to migrate to 3.3-V PCI or PCI-X slot motherboards," notes George Karones, the company's engineering manager.
There are now six models in Contemporary Controls's PCI20U Series of ARCNET network interface modules that link PCI-bus-compatible and PCI-X-bus-compatible computers with ARCNET local area networks (LANs).
The PCI20U Series also supports jumper-less configuration and is Plug-and-Play under Windows. Each module operates with either an NDIS driver or a null stack driver in a Windows environment.
Card dimensions are also in harmony with PCI's low-profile add-in card spec of 2.5 x 4.72-in. (64-mm x 120-mm). Both standard height and one-half height brackets are supplied with the 32-bit 33-MHz bus card.
The module's board also has two LEDs for monitoring network operation and bus access to the module. In addition, there's a DIP switch so that node addresses can be re-assigned without removing the module.
So, what will one of these PCI20U modules set you back? Contemporary Control Systems says they're priced at $245 a pop.
For more information, contact Contemporary Control Systems, Inc., 2431 Curtiss St., Downers Grove, Ill. 60515. Phone: 630-963-7070. Fax: 630-963-0109. E-mail: email@example.com