PLC Programmer Interview Questions and Answers for Freshers

Analog input and output devices are used to convert physical signals into electrical signals and vice versa in PLC systems.

• Analog input devices convert physical signals (such as temperature, pressure, or flow) into electrical signals for the PLC to process

• Analog output devices convert electrical signals from the PLC into physical signals to control actuators or devices

• Examples of analog input devices include temperature sensors, pressure transducers, and flow meters

• Examples o...read more

To return the largest and second largest numbers from an array

• Sort the array in descending order

• Return the first element as the largest number and the second element as the second largest number

A single push button can be used to turn a device on and off by toggling its state.

• Use a latch circuit to toggle the state of the device when the button is pressed.

• Implement a flip-flop to store the state of the device and change it when the button is pressed.

• Utilize a PLC program to monitor the button input and control the device output accordingly.

RS232 and RS485 are serial communication standards used for connecting devices in industrial automation.

• RS232 is typically used for short distance communication (up to 50 feet) and uses a single-ended connection.

• RS485 is used for longer distance communication (up to 4000 feet) and uses a differential connection for better noise immunity.

• RS232 uses DB9 connectors while RS485 uses RJ45 or terminal block connectors.

• RS232 uses a single-ended communication method, while RS485 uses...read more