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.
Reliability & Ease of Use
While IP's performance advantages may be clear on paper, foolproof network performance is something always strived for, yet rarely fully realized.
In the most basic sense, getting two electronic devices to talk to each other over a network merely requires setting a switch and a router. But client networks typically tie together a lot of equipment, and bandwidth often isn't big enough to handle it all.
Indeed, from bandwidth and latency issues to the intricacies of IP address management, corporate IT environments are often full of unpredictability, and AV pros frequently face a terrain in which communication speeds fluctuate unacceptably and devices inexplicably get kicked off the network.
Whether it's troubleshooting packet loss or trying to get through a firewall, for many AV operators, IT-world know-how is still a challenge, because they're often called to solve communication problems occurring over networks that are usually unique in both configuration and complication.
And even the most IT-savvy AV professional often faces a fundamental issue of project control, because they're beholden to an IT manager who has the final say on what can and cannot go on the company's network.
RS-232 constitutes a far simpler communication scheme, with no intermediaries to mess up the process–a fixed pipeline with dedicated speed and timing, far easier to troubleshoot and tested over decades.
In fact, for basic, localized AV systems, putting control on the network can be silly, since turning a device on and off hardly requires data transfer speeds of up to 10 Gbps.
Troubleshooting RS-232 communication breakdowns is a fairly straightforward proposition for AV integrators who have been working with the standard for years and often know right off the bat whether a problem is related to faulty wiring or software issues (the only two possibilities to be concerned with when using this control protocol).
In contrast to the complex, fast-evolving knowledge base needed to service IP-based systems, serial communication involves a more base-level programming skill set, with simple ASCII code being sent and received between device and controller.
Meanwhile, having been around so long, RS-232 is a widely adopted standard in the broader electronics industry, meaning a wide swath of both consumer- and pro-level device brands can be controlled via the protocol without any compatibility issues.
This factor can be difficult to assess, given the absence of clear apples-to-apples comparisons. Looking at things pedantically, factors such as adding serial ports and the rather considerable labor time of soldering RJ45 connectors can drive up the cost of an RS-232 scheme. And running a lot of RS-232 cable can be an impractical solution when a sufficient network backbone is available and need only have devices be connected to it.
But the cost differential between serial and Ethernet control schemes is a bit more complicated than comparing additional connector ports to routers and hubs, and at this point in the evolution of IP-based control systems, the price advantage must narrowly go to RS-232.
Indeed, many AV systems integrators are still somewhere on the learning curve when it comes to troubleshooting networks. And often, the labor costs associated with falling down the rabbit hole of a complex bandwidth or incompatibility issue can far out-strip the additional price of buying a bigger control processor or running some additional serial cable.
The simple fact that IP-based standards are still much more in flux that those of the staid RS-232 realm means that, in aggregate, AV integrators are signing onto a more complex labor proposition when they choose to go with the new technology.
Of course, as this newer technology evolves, and AV integrators continue to gain experience with it, IP-based solutions will certainly become less fraught with client service calls.