PLC Timer Instructions
A timer is a PLC instruction measuring the amount of time elapsed following an event. Timer instructions come in two basic types: on-delay timers and off-delay timers. Both “on-delay” and…
PLC Counter Instructions
A counter is a PLC instruction that either increments (counts up) or decrements (counts down) an integer number value when prompted by the transition of a bit from 0 to…
PLC Memory Mapping and I/O addressing
A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC they intend to program is how the digital memory of that…
What is Human Machine Interface (HMI) ?
Programmable logic controllers are built to input various signal types (discrete, analog), execute control algorithms on those signals, and then output signals in response to control processes. By itself, a…
Animation of Electromagnetic Relay
When a voltage is applied to the coil, a current passes through it and this creates a magnetic circuit which includes the core, armature and the yoke. The core attracts…
PLC Analog I/O and Network I/O
In the early days of programmable logic controllers, processor speed and memory were too limited to support anything but discrete (on/off) control functions. Consequently, the only I/O capability found on…
PLC Alarm and Trip Documentation
A vast amount of documentation is required for the design and construction of a process facility, which are front-end and detailed engineering drawings. The main engineering documents used on a…
Basics of PLC Programming
In the late 1960's an American company named Bedford Associates released a computing device they called the MODICON. As an acronym, it meant Modular Digital Controller, and later became the…
PLC System Documentation
PLC system documentsation includes PLC system overview, PLC wiring diagram, PLC Nest loading list, PLC Index, PLC datasheets, PLC GA drawings.
PLC Sequence Programming Ladder Logic
Write PLC program for Flare application using ladder diagram language using PLC Sequence Programming. Flare Control Valve application uisng PLC Logic.
