Analog signal

How it is used

Used with transmitters, analog input and output cards and drives. Engineers scale the raw value into engineering units, check for wire breaks (a current below 4 mA) and talk about resolution and noise. The opposite is a digital (on/off) signal.

Example sentences

1. The pressure transmitter sends a 4–20 mA analog signal to the PLC.

2. If the analog signal drops below 4 mA, show a wire-break alarm on the HMI.

Common collocations

• 4–20 mA signal
• analog input
• analog output
• scale the analog value
• signal noise

Related terms

• I/OShort for inputs and outputs: the signals a controller receives from sensors and buttons, and the signals it sends to valves, motors, lamps and other devices.
• sensorA device that detects a physical quantity or an event, such as position, distance, force, temperature or the presence of a part, and turns it into a signal a controller can read.
• PLCShort for programmable logic controller: a rugged industrial computer that reads inputs from sensors and switches, runs a control program and drives outputs such as motors, valves and lamps.
• process variableThe measured value of the quantity being controlled, such as the actual temperature, pressure or level, which the controller compares with the setpoint.

More terms: PLCs and Industrial Control

• HMI
• ladder logic
• relay
• scan cycle
• tag
• function block
• structured text