A programmable logic controller is a device with a processor capable of executing algorithms stored in its memory to activate/deactivate output signals (analog and/or discrete) based on input signals (analog and/or discrete) coming from field sensors.

If you are wondering where I have been, it has been 3 months of industrial projects, I have not had time for the usual electronic developments but I have had time for many industrial ones.However I refuse to let the blog die, especially when the currency experiences a big drop in price and it becomes important to keep the chain active with our articles and comments. So let's open a new chapter in the blog dedicated to industrial automation.

When we refer to microcontrollers or programmable controllers we will really find a huge variety in the market and the right one to use will depend on the needs of the project as well as the knowledge of the project developer.

Once given the articles Reading and writing EEPROM memory on PIC16F877A ENG/ESP and Circuit for Data Acquisition from a PT100 EN/ES we can use all the acquired knowledge and add the previous ones related to the use of microcontrollers to design a temperature transmitter with dual calibration adjustment.

Recently we addressed the temperature sensor LM34/35 in an article, one of the limitations that could be observed is that the LM34 can measure up to a maximum temperature of 150°C.There are many processes in which the temperature variable far exceeds this value, for this reason it is considered important to address a higher range element such as a PT100 that can measure up to 800°C and even more in other improved versions.

In the previous article we introduced the topic of the EEPROM memories in microcontrollers investigating its functions in a microcontroller and the importance it can have in the development of some projects.In this article we will go deeper into the subject making use of the EEPROM memory of the PIC16F877A, we will make a program that can store the data and we will see how to query the EEPROM memory data using the Proteus Software. We will also make a real application to check the permanence of the data in the memory after a power failure.