Controlled Decision: RS-232 vs.IP
Look at the back of any major-brand AV control processor these days and you'll probably see a snapshot of an industry in transition.
More and more AV devices now come with the regular RS-232 serial control port as well as network port for IP-based control. Witness an AMX Netlink controller (top), Crestron Adagio Digital Media System (middle), and Barco DCS-100 switcher (bottom).
While positioning a staid-yet-established standard like RS-232 next to a far more dynamic yet more volatile one like IP makes for an interesting comparison, it's likely that both schemes will continue to coexist within the AV business–and even be employed in conjunction–for years to come.
At this point in the evolution of both technologies, the decision to use one control technology over the other seems largely based on the integrator's comfort level and usage scenario.
For example, should a control system be subject to the whims of the network when all it has to do is turn a projector and some lights on and off in a single room? Conversely, for a sprawling system employing such tools as advanced videoconferencing, an integrator would be foolish not to leverage an advanced communications network that's already been built.
Over time, more and more devices, from disc players to coffee makers, will become network compatible, and IP standards will become more uniform. Eventually, like most technologies do, RS-232 will cede its ground and go away.
Still, even early adopters like Sensory Technologies' Brown recognize that traditional AV houses are not close to giving up on RS-232. "It's very comfortable for them because you're not getting into the complexities that inherent with network-based control," he explains. "Some of this stuff is still very intimidating."
Daniel Frankel is a freelance technology writer based in Los Angeles and a frequent contributor to Pro AV.
Best of Both worlds
For installations where RS-232 and IP coexist, or where serial-based control is gradually being migrated to IP, there are technology solutions that straddle both worlds.
Avocent (www.avocent.com), for instance, makes a variety of serial hubs that allow integrators and AV end-users to access RS-232, RS-422, or RS-485-connected devices. The company's ESP Serial Hubs come in 2-, 4-, 8-, and 16-port models (about $300 to $750 through various outlets). Internal Web servers allow you to manage the hubs and a Java-based ESP application can be used to remotely diagnose cable and device problems.
Magenta Research (www.magenta-research.com) sells very compact MultiView IP/Com interface modules (about 2.5 by 2.75 by 1.1 inches) for controlling and monitoring projectors, switchers, displays, and other serially controlled AV devices (RS-232 or RS-422).