Data types of Structured Text (ST)

Just like other programming languages, the IEC 61131-3 programming standard provides many different data types which include both elementary and complex ones. A data type defines how much memory capacity is needed by a variable value and by that, the largest and smallest value in the variable. 1 Elementary data types (INT, REAL, BOOL) The … Read more

HE599ETX200 Using the SmartRail Ethernet I/O with a ModbusTCP client (master)

Overview This application note describes the necessary configurations and settings to establish communications with the HE599ETX200 via ModbusTCP client applications.  This document covers: Boot-P Modbus addressing. ModbusTCP rules specific to the ETX200. Configuration words of individual I/O modules. Setup example using Modbus Poll software. Section 1 Modbus Addressing Input and Output I/O mapping I/O Data … Read more

Application note for English to Cyrillic translation via OCS

Overview This application note describes how to set up an English to Cyrillic translation using the Cscape Font Manager and Language Select functions.  It is a temporary application note in that the font support is likely to undergo improvements in future revisions of Cscape and will therefore look different and set up differently than what … Read more

Connecting plant power to DeltaV

Three-phase floating power for marine applications

The power and grounding practices in this article have been established over decades to provide excellent protection against electrical surges and transients in industrial installations. The electrical system installation must meet the local area codes and regulations to insure personnel safety and protection of property. The most common methodology is based on a solidly grounded … Read more

Emerson DeltaV I/O Sub-system Redundancy

Redundant I/O Card Types Redundant card types and terminations include: • Analog Input (AI) 8 channel 4-20mA with Hart • Analog Output (AO) 8 channel 4-20mA with Hart • Discrete Input (DI) 8 channel 24VDC Dry Contact • Discrete Output (DO) 8 channel 24VDC High-side • Serial Interface card 2 ports • FOUNDATION fieldbus H1 … Read more

Pump control with two pumps using Structured Text (ST)

Pump control with two pumps

This example describes a pump control with two pumps and three float switches in a well. The float switches are attached to cables and when the liquid rises in the well, the float switches will be activated and change their NC / NO position. The two submersible pumps M1 and M2 have been set to alternate operation mode, which … Read more

Simulation signals generated using Structured Text (ST)

Sine wave

This chapter describes simulation signals, which can be used during development and testing of the programming code. The machine or the hardware panel is often not available, when the PLC code and program needs to be tested. The hardware has possibly not arrived onsite, the machine is not built yet, or the PLC equipment is … Read more

Simple queue structure with Structured Text (ST)

ARRAY

This example describes the simplest implementation of a queue. A queue is used when e.g. there are many packages on a conveyer belt, waiting for treatment by a machine in a large plant. The packages often require information like weight, receiver, size or content. Weight gives information about a package which must be saved in … Read more

How the PLC executes PLC code ?

The basic mode of operation for a PLC

It is important to know how the PLC executes the program code when writing the program. A PLC executes the program in real-time, which means that the program modules must be executed within a short time-frame. The program modules are executed at a fixed time interval (the PLC scan time) e.g. 50 [ms]. Some of … Read more

Detailed Design of High Performance Displays

Schematic Example of a Level 3 Compressor Display

Many example depictions are shown conceptually and schematically because there is such wide variation in the display capabilities, characteristics, and arrangement paradigms of specific DCSs. There are major differences between DCSs regarding such commonplace things as controller faceplate access and display. It is the concepts and principles that are important, which are then applied to … Read more