Production systems need to be monitored because failure to do so can cause a delay in production due to a lack of remote monitoring. There are solutions that provide this information, but they are limited, because they are owned and very expensive solutions. This paper proposes the development of a mobile application for the monitoring of S7-1200 programmable controller variables through Firebase. The goal is to use open-source-type tools to develop a real-time variable monitoring application of a programmable controller capable of hosting a Web server, and the sent data to the Firebase cloud, in order to avoid modifying the driver software and the data stored in memory. The implemented system of sending, handling and presenting variables is developed with tools of open source type, since they have as an advantage to have greater freedom in programming, unlike proprietary solutions or services. The tests were performed on the Siemens S7-1200 controller with a plastic injection molding machine.