10
The procedure for manually moving a camera is as follows:
•
Reset motion voltages with the ‘R’ command.
•
Select and enable the camera with an ‘L’ command.
•
Move the camera using ‘P’, ‘T’ “Z’ and ‘F’ commands.
•
Disable the camera with an ‘L’ command.
The following 2 sections discuss the commands used.
Camera Selection and Enable
The ‘L’ command is used to enable the camera. It has a single numerical parameter
which corresponds to bits that are used to control switching of the camera. A pair of
bits is used to switch control to a given camera, and another bit determines whether
that camera is enabled for motion. The following table shows the selections performed
by the ‘L’ command:
Disabled
Enabled
Select Camera 1
‘L 0’
‘L 1’
Camera Control Voltages
Camera motion is controlled by four voltages corresponding to the velocity of pan, tilt,
zoom and focus which are set using the ‘P’, ‘T’ ‘Z’ and ‘F; commands respectively. (An
‘X’ command is also available to control the trolley, if used.) The commands have a
single numerical parameter determining the voltage to which the output is set. The
value of the parameter is in the range of 0 to 32767. A parameter value of 16383 is the
point at which no motion occurs. As the value moves away from 16383, the speed of
motion increases, and the direction of motion is determined by whether the value is
greater or less than 16383 as follows:
Command
< Less than 16383
> Greater than 16383
‘P’ Pan
Right
Left
‘T’ Tilt
Down
Up
‘Z’ Zoom
In (Tele)
Out (Wide)
‘F’ Focus
Near
Far
‘X’ Trolley
Track Right
Track Left
In addition, the ‘R’ command, which has no parameters, will reset all four control
voltages to the no motion value. This is useful to use before enabling a camera to
ensure that no motion will occur when it is first enabled.
There are many methods for determining control voltages. For instance, a joystick can
be used and the value it outputs converted to the range 0 to 32767 for control voltages.
