DCB Multiplexers Replace Legacy Products

Many older multiplexers manufactured by our historical competitors are no longer available for replacement purposes. Some of those companies dropped their multiplexer product line, others were forced out of business during economic downturns. DCB's SR and SPL series multiplexers are currently in production and are still being enhanced and improved with new features and technology. These are ideal replacements for orphaned or obsolete equipment. DCB's SR and SPL multiplexers are being installed on point-to-point and multi-drop DDS, frame relay, radio-link, T-1, analog, satellite, dial-up, fiber, and ethernet networks.

Although DCB multiplexers don't always interoperate with units from other manufacturers, our sales people are authorized to provide trade-in credit when replacing a pair of obsolete competitors with DCB multiplexers. Often, replacing a non-working orphan multiplexer unit with a pair of DCB multiplexers is less expensive than finding a replacement, used unit.

In addition to orphaned multiplexers, other current production and obsolete multiplexer brands such as Penril, Baytech, Comm Design, Micom, Multitech, Data Race, Timeplex, Codex, Racal, and others are also easily replaced with DCB products. Data Comm for Business is in the serial data management business. We are constantly improving and enhancing multiplexer technology, so when you are ready to upgrade or replace those older multiplexers, consider a modern replacement from DCB.

What is a Statistical Multiplexer?

Statistical multiplexers make it possible for multiple RS-232 devices to share a single data line. They also perform error correction to insure error-free transmissions. The term "statistical" refers to their ability to take advantage of the intermittent usage statics of most RS-232 devices (and all PC and terminal users). Because keyboards are idle a large part of each second with no one typing and no data being sent from the computer, each PC or terminal often averages less than 5% of its potential data rate. Statistical multiplexers allow the sum of the PC and terminal rates to exceed the composite link speed between the multiplexers.

The illustrations show a system without statistical multiplexers and how the same system would be configured with statistical multiplexing.

Without Multiplexing

With Multiplexing
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DCB manufacturers statistical multiplexers with two to thirty-two asynchronous ports that use either synchronous or asynchronous composites (the line between the two multiplexers), and that use either propriatary or frame relay protocols between the units.

DCB also builds multi-drop and multi-point statistical multiplexers. These systems allow multiple remote sites to all communicate with a single multiplexer at a host site when using multi-point or multi-drop wide area networks such as radios, multi-drop DDS lines, satellite, or frame relay.

Statistical multiplexers were developed to meet the needs of terminal (and later PC) users. In the last few years, they have found new applications in many fields of machine-to-machine communications. It is now common to see statistical multiplexer networks with no PC or terminal connected. Some common uses are sharing one line between multiple point-of-sale terminals (cash registers), printers, networked computers using PPP or SLIP, lottery machines, SCADA systems, security systems, gaming machines, or process control equiment.

In some cases, routed networks share wide area network (WAN) links with older terminal based networks by conecting a router on one port of an older statistical multiplexer network. This allows simultaneous use of remote terminals along with LAN workstations for email and provides an orderly transition path from terminals to LAN based workstations networks. In other cases, DCB multiplexers are used to transport serial data via ethernet connections using our EtherPath ethernet interface.

Most statistical multiplexers use a proprietary protocol on the "composite line" between the two units. At DCB, we've also added frame relay as a native composite protocol. This allows DCB multiplexers to operate over a native frame relay point-to-point or point-to-multipoint network. It even co-exists with Cisco brand routers!

Most statistical multiplexers also require a full duplex link between the two units. DCB has a line of data concentrators (special breed of statistical multiplexer) that function over a simplex or half-duplex link. This system works more efficiently over radio and satellite links.

DCB has been building statistical multiplexers since 1981. Along with the expected incremental improvements of faster speeds, open standards, lower cost, and more processing power; many unique features have been added to our statistical multiplexer line. We even added low bit rate voice multiplexing to our SR series.
For example, many of our statistical multiplexers support "AT command spoofing". This allows Windows95 PCs and other workstations to use PPP connections through a multiplexed WAN link. This feature is often used with frame relay to extend LAN connectivity to PCs at multiple locations with no ethernet cards or routers. Many other features have been added to enhance ease of configuration, problem diagnosis, remote training, and performance.

Links to DCB multiplexer product datasheets...
Link to other DCB products.
Link to other DCB educational material.
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Data Comm for Business Inc.
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