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…
PLC Analog Signals Wiring Techniques
Unlike the discrete/digital (on/off) circuit, analog signals vary across a range of voltage or current. Taking the same vessel described previously in Digital wiring example, how would the wiring change…
PLC Problems Troubleshooting
Troubleshooting PLCs can be started by checking the healthiness status of CPU, I/O Modules, Fuse Blow-out and different PLC Failure reasons including wiring, field transmitters healthiness status or transmitter configuration,…
How PLC Reads the Data from Field Transmitters
Instrumentation and control rely on converting physical or process variables into a more useful format for the operator display. Pressure in a pipe is converted to mechanical deflection of a…
How a PLC do the Scaling for a Sensor ?
I am always surprised how an automation system like PLC or DCS does the scaling for a sensor ? or even sometimes thinking about a simple field transmitter scaling techniques…
