These permanently mounted cameras monitor for instantaneous violations of maximum speeds. If a Red Light Camera Installation monitors Speed Limit Violations, there is no need to add a separate Speed Camera.
The Max Speed for a Speed Camera should be set to the speed limit for the road which the speed camera is monitoring. Leave the max speed set to blank if speed is not monitored. Zero is not blank; a max speed of zero will cause the camera to always generate an audible alert.
Red Light Camera
Permanently mounted cameras monitor for red light violations and optionally for violations of maximum speeds.
On Combined cameras - camera's who are monitoring both speed and red light violations - the maximum speed should be set to zero. If the maximum speed is set to zero it forces in all circumstances an audible warning.
Sometimes a fake device is placed. Dummy cameras are sometimes added to prevent people from reporting these as actual cameras.
In the app a dummy camera looks like this one: