Communication Transmission Solution for Tunnel Lighting Control
Communication Transmission Solution for Tunnel Lighting Control
1 Requirements Analysis
A tunnel lighting control transmission system consists of a control computer (monitoring and management software), dimming controllers, dimmable luminaires, an external brightness detection device, and a fiber optic transmission system.
The external brightness detector transmits the detected brightness signal outside the tunnel to the entrance-section dimming controller, which then uploads it to the control computer. After performing logical calculations on the collected external brightness data, the control computer determines the required brightness level and issues dimming commands to each dimming controller. The dimming controller converts the required brightness level into a DC 1–10 V analog signal output to control the voltage-controlled current source on the LED luminaires (output-current-controllable LED driver), thereby adjusting the luminaire brightness.
The control computer can be located in the tunnel monitoring room, exchanging data with the on-site dimming controllers via the fiber optic transmission switching network. Different dimming controllers are distinguished by their addresses. Dimming between the dimming controllers and LED luminaires is achieved using DC 1–10 V analog voltage.
The control computer can also be located at the road monitoring center, connecting to the tunnel fiber optic transmission switching network via the IP transmission network to exchange data with the on-site dimming controllers.
2 Solution Design
Based on the requirements analysis, the system design is as follows:
In this solution, the main transmission adopts a 250M fiber optic ring network. An integrated service optical multiplexer IDM MP200-30E is installed in the tunnel monitoring room, and several access-type optical transmission devices IDM NTD421 are installed at the tunnel entrance, exit, and on both sides inside the tunnel.
Each access-type optical transmission device IDM NTD421 provides 2 RS485 interfaces for serially connecting multiple dimming controllers in the tunnel. The integrated service optical multiplexer IDM MP200-30E in the tunnel monitoring room connects to the IDM MPCONV serial server via an E1 interface, thereby aggregating all RS485 signals in the tunnel.
The serial server connects to the lighting control center via an IP interface, linking to the control computer, and the tunnel lighting is controlled through lighting control software.
3 Solution Features
The devices selected for this system support both chain and ring network topologies. This simplifies cable installation and, in the event of a fiber optic cable interruption, the self-healing ring network ensures uninterrupted service transmission.The central-end device has the capability to aggregate multiple RS485 services into one IP port and to aggregate Ethernet services.It also provides corresponding access means for security surveillance and emergency communication after future expansion.