At the traffic light facility in the city of Ternopil, traffic lights with new countdown time boards are installed, which, in the mode of operation from pedestrian call-out sign work in, control modes from road controllers:
- On the power line: "Wait".
- Via RS485.
The countdown timer board can function as a completely autonomous device and its use does not require the refinement and modification of road controllers, and in this mode the road controllers are connected to the countdown timer board only by power traffic signals. But it is more functionally possible to use the countdown board with the additional use of the RS-485 interface, and for this, road controllers must be equipped with a suitable RS-485 interface converter and must have appropriate support at the controller software level (to support communication protocols between the road controller and the countdown board). When using the RS-485 interface, it is possible to dynamically change the time intervals of the traffic signals set by the traffic controller, depending on the road conditions and the intensity of traffic, while the real-time countdown board displays the time according to the changed time intervals of the traffic signals. When the time countdown board with the "pedestrian calling board" button works in offline mode, an additional "Wait" signal is required, and when using the RS-485 interface, the "Wait" signal is not used in the time countdown board.
Modes of operation of the time countdown board with the "pedestrian call sign" or "traffic signal calling device" button:
- Autonomous time display mode, using the "pedestrian call sign" or "traffic signal calling device" button on the traffic light object (activated after pressing the "pedestrian call sign" button). In this mode, the countdown board independently measures the time intervals of traffic signals (red, yellow, and green), but only after the "pedestrian call sign" button is activated (information about the activation of the "pedestrian call sign" button is transmitted from the traffic controller to the countdown board with an additional signal - "Wait"). When the "pedestrian call sign" button is inactive, the countdown signboard displays two lines (for a traffic countdown signboard) or a pedestrian symbol (for a pedestrian countdown signboard) on the signboard. The operation mode with the "pedestrian call sign" button is set in the countdown board either in advance or by a special command on the RS-485 interface in service mode, or by installing jumper X2 on the countdown board. In this mode, the countdown board is connected to the road controller through the following minimum electrical connections: a four-wire cable (for pedestrians) or a five-wire cable (for transport), with power traffic signals - red, yellow (for transport), and green, with one neutral and one additional power signal "Wait". If necessary, an additional power signal can be added to power the countdown board from a separate power supply (220V 50Hz), which is controlled by a road controller on one of the power outputs.
- Time display mode based on RS-485 interface commands from the traffic controller, using the "pedestrian call sign" or "traffic signal calling device" button on the traffic light object. In this mode, the time value equal to "0" is sent from the road controller to the countdown board via the RS-485 interface every second when the "pedestrian call sign" button is inactive, while the countdown board displays two lines on the board (for a transport countdown board) or the symbol of a pedestrian (for a pedestrian countdown board). When the "pedestrian call sign" button is activated, the countdown time value displayed on the board is sent to the countdown board every second for two traffic light cycles, after which the board again displays two lines (for a traffic countdown board) or a pedestrian symbol (for a pedestrian countdown board) until the next activation of the "pedestrian call sign" button. To enable this mode of operation in the countdown board, the address of the countdown board at the traffic light object (from 1 to 32) needs to be programmed in service mode (according to the documentation for the road controller or the countdown board module). In this mode, the countdown board is connected to the road controller through the following minimum electrical connections: a three-conductor cable (for pedestrian) or a four-conductor cable (for transport), with power traffic signals - red, yellow (for transport), and green, with one neutral, as well as a shielded cable with a twisted pair, with two RS-485 interface signals (RS485-A and RS485-B) and with a contact to the cable shield. If necessary, an additional power signal can be added to power the countdown board from a separate power supply (220V 50Hz), which is controlled by a road controller on one of the power outputs.
For additional information and questions regarding the purchase of traffic lights and technical means of traffic control, please contact SEA Company office by phone: +38 (044) 330 00 88 or write to the mail: info@sea.com.ua