In industrial automation, PLCs serve as essential for monitoring and controlling processes. While digital signals are simply ON or OFF, numerous industrial applications need accurate control over factors like
• Temperature,
• Pressure, &
• Motor speed.
This is wherein analog values come into play, and knowing how PLCs read & process them is important for improving performance and dependability.
PLCs read analog information using specialized hardware known as Analog Input Modules.
These modules are intended to communicate with
• Sensors &
• Transmitters
that generate continuous signals, usually in form of voltage (0-10V) or current (4-20mA).
Because Programmable Logic Controllers (PLCs) function digitally, the initial step in applying an analog signal is converting it to digital representation.
This is performed using an Analog-to-Digital Converter (ADC) in the input module.
The ADC samples the incoming analog signal at frequent intervals and gives it a digital value based on a specified resolution, which is typically 12-bit or 16-bit, determining how finely the signal can be represented.
The raw digital data received by PLC is often in a numerical range, such as 0 to 4095 in a 12-bit system.
Engineers and operators, on the other end, require this data in useful engineering measures like degrees Celsius (or) bar pressure.
Here’s where scaling comes in. The PLC program uses a mathematical conversion to convert the raw input value into a meaningful measurement that correlates to the physical parameter under observation.
Most PLC programming environments include built-in functionality to facilitate the scaling process and ensure accurate representation of sensor data.