SIS Sensors
Perhaps the simplest form of sensor providing process information for a safety instrumented function is a process switch. Examples of process switches include temperature switches, pressure switches, level switches, and…
SIS Final Control Elements
When a dangerous condition in a volatile process is sensed by process transmitters (or process switches), triggering a shutdown response from the logic solver, the final control elements must move…
What is Safety Instrumented Functions ?
A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific safety-related task in the event of a specific dangerous condition. The over-temperature shutdown switch…
PLC Logic for Automatic Bending Machine for Exhaust Pipe
Automatic bending machine This is PLC Program for automatic bending machine for exhaust pipe. Problem Description The bending of exhaust pipes is to be controlled using PLC. The bending procedure…
What is SCADA ? How does SCADA Works ?
SCADA stands for Supervisory Control and Data Acquisition but it is a term often used for data collection and presentation. What is SCADA ? SCADA is normally a software package…
Normally-open and Normally-closed Switch Contacts
Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status. Electrical switch contacts are typically classified as either normally-open or normally-closed, referring to the open…
Failsafe Wiring Practices
Failsafe wiring practice is one of those topics that separates control system designers and electricians from other technical specialties. This is one of the areas that show up as problems…
PLC Analog Input Card Resolution Effects on Accuracy
An instrumentÂ’s accuracy is limited by its precision. An instrumentÂ’s precision is determined by making minute variations in the measured process variable (e.g., pressure, temperature) and then monitoring the instrumentÂ’s…
PLC Analog Input Conversion Formula
For any unit conversion on any PLC, you can use four function math with the following for PLC Analog Input Conversion Formula, which assumes integer math, as follows : PLC…
PLC Digital Signals Wiring Techniques
Ina process plant, on/off control is done through the PLC or DCS. The below Figure is an overview of one discrete/digital (on/off) circuit, showing the entire process from the power supply…
