In this paper, digitally controlled hybrid liquid level detection (HLLD) system using programmable logic controller (PLC) and microcontroller is articulated. In most of the industries, liquid (chemicals, paint, water, etc.,) is stored at ground levels or in underground tanks and then pumped into overhead tanks as per requirement. This method is advantageous because it is very easy to unload tanks of liquid into underground tanks, and liquid can be pumped as per its necessity. PLC is excellent industrial controller which is used for pump control along with its analog module interfaced to sensor for level detection. This system is efficient but very costly because of analog module. Proposed system eliminates the analog module and replaces it with an embedded microcontroller. In proposed system, PLC analog module is replaced by Arduino microcontroller. This reduces cost of system very much, even the sensors used with microcontroller are comparatively very cheap than those used with PLC directly. In the proposed mechanism, supervisory control and data acquisition (SCADA) system is also interfaced with PLC which monitors the level of liquid and logs the data of liquid usage for analysis. This paper gives detailed information of proposed system along with flowcharts, algorithms, and hardware implementation with actual result of SCADA system.
