PTZ cameras are security cameras that have the ability to change their positions, depending on the PTZ camera type, you can Pan Tilt and Zoom the camera remotely.
For the technology to work the DVR systems, controller keyboard and PTZ cameras have to run on the same protocol and interface before they can communicate. When looking to purchase PTZ camera equipment, please make sure they are compatible. Pelco D protocol with RS485 interface is the most common way to interface and control a PTZ camera.
PTZ Camera Connection Diagram Interface between devices: For the DVR system to communicate with the camera, Command protocol has to be transmitted from the DVR or controller keyboard through an interface conduit to the PTZ camera. RS485 or RS232 are the common interfaces for PTZ that are done by running a single pair or twisted pair cable from the DVR to the PTZ camera. An RS232 is usually used when it is at a very short distance. RS485 interface can work over very long distances, and is used by most PTZ cameras. Most of the standalone DVR’s have RS485 interface. PC based DVR have an RS232 interface with a converter to RS485.
DVR’s, whether it’s a PC based or Standalone DVR need to send out command signals to PTZ cameras to control pan, tilt or zoom. In the other side the PTZ camera must understand these commands to be able to follow the instructions. To enable the two devices to understand each other, they need to speak the same language, which is called a PROTOCOL. The most common protocol for PTZ cameras is the Pelco D. If you are planning to purchase security DVR system and PTZ security cameras, please make sure they support the same protocols.
Multi PTZ camera. Installation of more then one PTZ camera on the same CCTV system you need to tell the DVR how to differentiate between the cameras. This feature will let you control specific cameras without affecting the others. PTZ cameras have dip switches that you can select different camera addresses for example: camera 1 ID=1, camera 2 ID=2, Camera 3 ID= 3 etc. Check your camera manual for instructions how to setup camera ID.
Connecting a PTZ camera to a DVR
To connect a PTZ camera to a DVR, you need three types of cable ( See diagram)
- Power cable mostly reffered to as 18/2 to send 12V or 24V power to the camera ( If you are using Siamese cable, it will have both Power and Coax in one). Connect from the power supply to the DC or AC connector on the security camera.
- RG59 Coax. Connects from the BNC connector on the camera to the BNC camera in on the security DVR this is the Video signal cable, which will send the video signal from the camera to the DVR.
- Pair / Twisted Pair cable. Any copper pair cable that will send the PTZ command from the DVR to the PTZ camera. This cable connects from the RX+ RX- on the PTZ camera to the RS485 connector on the Security DVR or PC Based DVR.
On the Security DVR whether it’s a standalone or PC based, you need to set the devices protocol, baud rate, and camera ID on the DVR depending on the specs provided to you by the camera manufacture. Of course, all PTZ camera IDs on the same system have to be unique. Make sure to map the camera inputs with the corresponding IDs.
If you are installing multiple PTZ cameras on one DVR system, please be careful of the wiring scheme for RS485 interface. There are two ways:
1. All the Coax cable RG59 and Power run from each camera to the Security DVR or PC based. All twisted pairs would run from each camera and combine all the RX+ from all the camera and the RX- from all the cameras and connect to the same interface on the RS485 on the DVR (Please sure that the polarity for the twisted pair is right). The longest run cable would have to be terminated with a resistor,
2. Daisy chain: Run the twisted pair from the RS485 interface on the security DVR to the closest security camera, then, from this camera to the next PTZ camera, and to the next camera until you get to the furthest camera.