20+ Sheela Foam Interview Questions and Answers

Modbus is a communication protocol used in industrial automation. It allows communication between devices connected to a network.

• Modbus is used to transmit data between devices in a master-slave architecture.

• There are two types of Modbus: Modbus RTU (serial communication) and Modbus TCP (Ethernet communication).

• Modbus RTU supports up to 247 slaves while Modbus TCP can support thousands of slaves.

• Modbus is commonly used in industries such as manufacturing, oil and gas, and ene...read more

ASI protocol is a serial communication protocol used in industrial automation systems.

• ASI stands for Actuator Sensor Interface.

• It is used to connect sensors and actuators to a central controller.

• It is a simple and cost-effective protocol.

• It supports up to 62 slaves per master.

• It uses a 2-wire bus for communication.

Watchdog timer is a safety mechanism that resets the system if it fails to respond within a set time. System overhead time is the time required for the system to perform non-critical tasks. RPI is the rate at which the PLC scans its inputs and outputs.

• Watchdog timer is used to prevent system failures due to software or hardware issues

• System overhead time is the time required for the system to perform non-critical tasks such as updating the clock or handling interrupts

• RPI is t...read more

RS Linx is a software used for communication between Rockwell Automation devices. It includes drivers and FactoryTalk Linx.

• RS Linx is a communication software used for Rockwell Automation devices

• It includes drivers for various devices such as PLCs, HMIs, and drives

• FactoryTalk Linx is a component of RS Linx that allows communication between devices and software applications

• RS Linx supports various communication protocols such as Ethernet/IP, ControlNet, and DeviceNet

Standard HMI for basic operations, Performance HMI for complex operations.

• Standard HMI for simple and routine operations

• Performance HMI for complex and critical operations

• Performance HMI for high-speed processes

• Standard HMI for low-speed processes

Kepware is a software solution for industrial automation communication.

• Kepware is used to connect different industrial devices and software applications.

• It supports various communication protocols such as OPC DA, OPC UA, MQTT, etc.

• OPC DA is a legacy protocol used for communication between Windows-based applications and process control hardware.

• OPC UA is a newer and more secure protocol that supports cross-platform communication and data modeling.

• Kepware provides a user-friend...read more

Different protocols used in automation engineering

• Modbus

• Profibus

• DeviceNet

• Ethernet/IP

• CANopen

• AS-Interface

• Foundation Fieldbus

• HART

• BACnet

• LonWorks

Communication between SCADA/HMI & PLC is crucial for automation. It enables real-time monitoring and control of industrial processes.

• SCADA/HMI sends commands to PLC for process control

• PLC sends data to SCADA/HMI for real-time monitoring

• Communication protocols like Modbus, Profibus, and Ethernet/IP are used

• Redundancy and fault-tolerant systems are implemented for reliability

Unicast and multicast are communication methods used in produce consume tag.

• Unicast is a one-to-one communication method where a message is sent to a single recipient.

• Multicast is a one-to-many communication method where a message is sent to multiple recipients.

• Produce consume tag is a mechanism used in automation systems to communicate between producers and consumers.

• Unicast is used when the producer needs to send a message to a specific consumer.

• Multicast is used when the p...read more

PLC programming tasks involve designing, coding, testing, and maintaining programs for industrial automation systems.

• Designing and coding ladder logic diagrams

• Testing and debugging programs

• Maintaining and updating existing programs

• Collaborating with other engineers and technicians

• Documenting programs and processes

OPC communication is a standard protocol used for data exchange between different industrial automation systems.

• OPC stands for OLE (Object Linking and Embedding) for Process Control

• It allows communication between devices from different manufacturers

• OPC servers provide data to OPC clients using a common language

• OPC UA (Unified Architecture) is the latest version of OPC with improved security and scalability

Rockwell Software used names for their software products instead of version numbers.

• Rockwell Software used names like RSLogix, FactoryTalk, and Studio 5000 for their software products.

• This naming convention made it easier for customers to identify and differentiate between different software products.

• The names also helped to create brand recognition and loyalty among customers.

• Rockwell Software continues to use this naming convention for their software products today.

The memory of the controller used depends on the specific controller model and manufacturer.

• The memory capacity can range from a few kilobytes to several gigabytes.

• Some common types of memory used in controllers include RAM, ROM, and flash memory.

• The memory is used to store the program code, data, and configuration settings.

• Examples of controller manufacturers include Siemens, Allen-Bradley, and Schneider Electric.

Datalogging in SCADA refers to the process of recording and storing data from various sensors and devices in a SCADA system.

• Datalogging is important for analyzing trends and identifying issues in a SCADA system

• Data can be logged in real-time or at set intervals

• Logged data can be used for reporting, troubleshooting, and optimization

• Examples of data that can be logged include temperature, pressure, flow rate, and energy consumption

Alarm creation in SCADA involves setting up thresholds and triggers for abnormal conditions.

• Define the parameters for triggering an alarm

• Set the threshold values for each parameter

• Configure the alarm notification system

• Test the alarm system to ensure proper functionality

Priority among tasks is determined based on their urgency and importance.

• Tasks with high urgency and high importance should be given top priority.

• Tasks with low urgency and low importance can be given low priority.

• Tasks with high urgency but low importance can be delegated to others.

• Tasks with low urgency but high importance should be scheduled for later.

• Prioritization should be reviewed regularly to ensure tasks are still relevant and important.

Produce consume tag is a synchronization mechanism used in multi-threaded programming.

• It is used to ensure that a producer thread does not overwrite data that has not yet been consumed by a consumer thread.

• The producer thread sets the produce tag when it has produced new data.

• The consumer thread sets the consume tag when it has consumed the data.

• The producer thread waits for the consume tag to be set before producing new data.

• The consumer thread waits for the produce tag to b...read more

Supply chain management in E & I involves coordinating the flow of electrical and instrumentation materials and equipment from suppliers to end-users.

• Procurement of electrical and instrumentation materials and equipment

• Inventory management to ensure availability of required items

• Transportation and logistics to deliver materials to project sites

• Coordination with suppliers to ensure timely delivery

• Quality control and inspection of received materials

• Documentation and record-keep...read more

JWT signature is a string of characters used to verify the authenticity of the token.

• The signature is created by hashing the header and payload with a secret key.

• The resulting hash is then encoded using Base64Url encoding.

• The signature is added to the token as the third part, separated by dots.

JWT is a JSON-based token used for authentication and authorization purposes.

• JWT stands for JSON Web Token.

• It consists of three parts: header, payload, and signature.

• Header contains the algorithm used to sign the token.

• Payload contains the user information and metadata.

• Signature is used to verify the authenticity of the token.

• JWT is stateless and can be used across multiple domains.

• Example: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lI...read more