I'm building camera systems to mount on top of a TV tower. When storm clouds roll, in the video is displayed on the TV weather report. No one wants to climb the tower to manually pan and tilt and zoom and focus the camera during a thunderstorm, so we control them remotely. Currently I control the systems with Pelco D protocol over RS485.
I'm building some camera systems that are capable of variable-speed pan, tilt, zoom, and focus. (PTZ). (The prototype has an Arduino that controls the zoom and focus motors).
Alas, my ancient copy of the standard Pelco D protocol (and the earlier Pelco P protocol) doesn't have a way to tell the camera what speed to zoom or focus. (The only variable-speed stuff it supports is variable-speed pan and tilt). So currently I hard-wire the speed, which everyone agrees is the wrong speed. About half the people say it's too fast, and the other say it's too slow :-). It would be much easier to frame a shot and focus if we could take advantage of the hardware I already have to do variable-speed control.
I control both ends of the RS485 cable, so I could make up yet another random protocol.
- Is there a standard or semi-standard extension to the Pelco protocol that supports variable-speed focus or zoom or both?
- Is there a good way to extend the Pelco protocol in such a way that, when I add a new cameras and a new camera controller to a common RS485 bus, they don't conflict with old cameras and old camera controllers already on the bus; and are less likely to conflict with new extensions others may add later?
- Is there maybe some other standard protocol for controlling TV cameras, preferably ones that support variable-speed zoom? Wikipedia says that Pelco D is used in "infancy". Are better protocols are available? If so, how do I get the information I need to implement those protocols in my camera systems?