Signal control system based on PLC

The invention relates to the technical field of signal control, and discloses a PLC-based signal control system, which comprises an external vehicle sensing system, a central control system for signal adjustment and presetting, and a signal control system for signal output, the vehicle sensing system, the central control system and the signal control system are connected through network signals; vehicle detection and traffic signal adjustment are performed on an intersection through the vehicle sensing system and the central control system, and the phase budgeting module judges whether to prolong the green light interval time length of a specific phase or shorten the phase interval without traffic requirements according to vehicle data collected by the dynamic detection module, so that the purposes of ensuring the traffic stability and improving the traffic safety are achieved. The vehicle release in a period of time is maximized, the parking frequency is ensured to be minimum, the trouble of commanding and a