Energy audit is a systematic process to understand how and where the energy is being used. From the audits, energy auditor can identify the energy saving potential and can decide energy management tasks base on the report. However, there are several important challenges need to be considered in conducting energy audits especially in collecting field data at the multiple locations with various parameters. Previously, energy auditors need some number of data loggers in order to log the data from different parameters such as voltage, current, temperature, humidity and lux. The loggers come from various brands, software’s and purposes. This inefficient process cause the unsynchronized date and time, different logging period and logging time interval which consequently leads to high cost of equipment used, manpower, time consuming and low accuracy of data taken. The aims of this project was to develop a tool dedicated to energy auditor to improve the energy audit process during field data collection named variable input/output data logger that combined various parameters under one tool. This project utilized Field Programmable Gate Array board (FPGA) on the design part using platform designer software (QSYS) to generate the Verilog coding in the Quartus Prime Lite software and Altera DE1-Soc development board for the prototype. In this project, the developed data logger had the ability to measure and logged three essential parameters that would be used for energy analysis which were voltage, current and temperature. The results showed all the parameters worked concurrently and time synchronized controlled by only one data logger. The time interval for each parameter can be easily set to the any other counting at the clock set in the Qsys software. Lastly, the logged data from the logger could be displayed in real time when connected to computer for immediate observation and also could be saved systematically in Excel format for energy report analysis. This project benefits energy auditor for their auditing works and report preparation in term of time consume, cost and increase data reliability due to synchronization of date and time.