# What does 16-bit resolution mean in PLC?

In the context of Programmable Logic Controllers (PLCs), “16-bit resolution” refers to the data representation capability of the analog input module used to interface with sensors, such as process signal transmitters. A 16-bit resolution means that the analog input module can convert the analog signal from the process flow transmitters into a digital value with a precision of 16 bits. This level of resolution allows PLCs to accurately measure and process the flow rate of a fluid in various industrial applications.

## Flow Transmitter and Analog Signal

• In the water treatment plant, the flow transmitter is a sensor responsible for measuring the flow rate of water in a pipe.
• The flow transmitter generates an analog signal, typically in the form of a current (4-20mA) or voltage (0-10V) proportional to the flow rate.
• The actual flow rate can vary depending on factors like pipe diameter, pump speed, and valve position.

• Before the PLC can process the flow rate data, the analog signal from the flow transmitter must be converted into a digital value.
• This conversion is performed by the analog input module of the PLC, which has a 16-bit ADC.

## Resolution and Digital Value

• A 16-bit resolution means that the ADC can divide the analog signal’s range into 216 (65,536) discrete levels. In the case of a current signal (4-20mA), the ADC maps the current range (4mA to 20mA) to these 65,536 levels.
• Each level corresponds to a unique digital value. For example, if the flow transmitter is outputting 12mA, the ADC will convert it to a specific digital value, say 32,768.

## Flow Rate Measurement

• The PLC receives the digital value from the analog input module and performs further calculations to interpret the flow rate.
• The PLC knows the calibration settings of the flow transmitter, which helps it convert the digital value into an actual flow rate in liters per minute (LPM), gallons per minute (GPM), or any other applicable unit.

## Control Logic and Decision Making

• The flow rate data obtained from the flow transmitter can be used by the PLC’s control logic to make decisions and perform specific actions.
• For instance, if the flow rate exceeds a predetermined threshold, the PLC may trigger a valve to adjust the flow, activate an alarm, or stop a pump to maintain a safe and controlled flow in the water treatment process.