The Nuts and Bolts of PLC Mapping
2. How Mapping Actually Works
Okay, so we know mapping is important, but how does it actually work? Well, it's all about connecting the digital world of the PLC program to the physical world of sensors, actuators, and other devices. It involves creating a correspondence between the PLC's internal memory locations and the external input and output points.
Typically, you'll use the PLC programming software (every manufacturer has its own flavor) to define variables. These variables represent the inputs and outputs of your system. You then assign these variables to specific memory locations within the PLC. For example, you might create a variable called "Motor_Start_Button" and assign it to the input "I0.1." Now, whenever the PLC sees a signal on input "I0.1," it knows that the "Motor_Start_Button" is being pressed.
The mapping process also involves defining the data type of each variable. Is it a boolean (on/off), an integer, or a floating-point number? This tells the PLC how to interpret the signal. You might also specify the engineering units (e.g., degrees Celsius, PSI) for analog inputs and outputs, allowing the PLC to display and process values in a meaningful way.
Think of it like labeling all the switches and buttons in your house. Instead of just having a bunch of unlabeled switches, you know exactly which one controls the living room light, the fan, or the garbage disposal (hopefully, those are on separate circuits!). PLC mapping does the same thing for your industrial automation system.
