How to gather data to measure the OEE of machines in the production line effectively?

measuring OEE needs valid data from the bottom of the shop floor, gathering the right information leads to the right calculation, so the most important step of OEE software is the data gathering step, the more right valuable valid data, the more accuracy of calculation on the software, to input right data we have some methods;

Manual entry

Many companies currently have a person in charge of gathering data from the shop floor, this person do counting parts, total defective parts for a period of time, takt time, reasons for downtime and etc. then she will inputs these data into an excel file and make some calculation and finally share the file with managers and other people, there are some pros and cons over this type of data gathering,
to pros, there is no need to add more capital,  it's simple to conduct, and descriptive data can be added, in another hand, it needs human resources to accomplish, the security is very low, it may affect by human errors and leads to false data, it's highly dependent to human and it's availability, and also human should be very conscious about the accuracy of data

Manual scanning of barcodes or QR codes

adding numbers and reports by keyboard is somehow frustrating in long-term, in that case, and if the factory needs humans to be in charge of data entry, it's recommended to use QR-code scanners for batch scanning, like a cashier in a mall, if the human at the beginning of the line, attach QR-codes correctly to the system, scanners can be installed as in a fixed position

Watcher and other sensor-based hardware

in case the factory was machine intensive, or it needs the operator fully concentrate on their job rather than data entry, it'd be better off to implement automatic data gathering hardware like Watcher-jet®, these machines get the signals and related information directly from the machine with an electrical isolated connection and without human intervention, these Watchers can be installed as plug and play options or directly to Actuators, they sent their data to the software automatically via Wire-less, Celluar, or Lan cables, in advanced watchers, they collect other machine metrics like electrical current and temperature and do some edge processing for advance applications like Predictive Maintenance or Incident Identification

Watcher-cam and other camera input data

in Some cases which stations are visible from a camera or due to station conditions, it's been recommended to use WATCHER-CAM, to screen live shows of the station, and use these video data to collect data from the production line and its status, these videos help to identify the number of parts, the speed of production line, the quality of the products and the overall view of the station

OMS

in labor-intensive stations, and complicated operations of human (like assembly lines) it's better to use technical software like OMS® which creates a fully comprehensive view of the stations for the software and its history

it doesn't matter how you gather data until you know that you've provided with valid and good pace data-gathering system, if you have labor and you don't consider the slow speed of labor to provide data, manual data gathering is more convenient if you had a high price and fast speed machines, you'd better provide with Watchers, the more precious your final product goes, you'd better go to AI-based algorithms, all in all, providing data is an inevitable step through your factory digitalization journey