Main function:
. It is to inquire about the relevant sensors status via RS485-B by turns, and forward the data to CCU by RS485-C.Meanwhile, the
ZCU forwards the command of CCU to LED screen via RS485-B.
. The RS485-B data bus can support 60 UD in max., whose addresses must not be set repeatedly.

How Parking Guidance System Works:
Firstly, UD takes use of ultrasonic wave to detect the car space to see if it is occupied by vehicles and transfer relative command to LED Indicator which will turn from green to RED when occupied, or it will keep GREEN; meanwhile, the UD transmit its status message to ZCU immediately, and ZCU will collect and forward the information to CCU; CCU processes these data and sends the relevant command to ZCU and LED panel.