PLC programming, tutorial, training, hints and tips.

Output cards again require some form of isolation barrier to limit damage from the inevitable plant faults and also to stop electrical ‘noise’ corrupting the processor’s operations. Interference can be more of a problem on outputs because higher currents are being controlled by Computers and industrial

Computers and industrial control 25 the cards and the loads themselves are often inductive (e.g. solenoid and relay coils). There are two basic types of output card. Eight outputs are fed from a common supply, which originates local to the PLC cubicle (but separate from the supply to the PLC itself). Read the rest of this entry »

Internally a computer usually operates at 5 V DC. The external devices (solenoids, motor starters, limit switches, etc.) operate at voltages up to 110 V AC. The mixing of these two voltages will cause severe and possibly irreparable damage to the PLC electronics. Less obvious problems can occur from electrical ‘noise’ introduced into the PLC from voltage spikes on signal lines, or from load currents flowing in AC neutral or DC return lines. Differences in earth potential between the
PLC cubicle and outside plant can also cause problems.

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The complete command listing for this ladder rung including termination commands is:
LD IN1 ENTER
AND IN2 ENTER
STO OUT1 ENTER
The commands may be entered using a hand-held programmer, dedicated desktop programmer or a computer containing software that will allow it to operate as a programming device. Each controller command line contains (1) a command, (2) the object of the command and (3) a terminator (the ENTER key). In the case of the first line, LD is the command, IN1 is the object of the command and the ENTER key is the terminator. Read the rest of this entry »

Introduction
All discussions in previous sections have considered only the ladder diagram in all program example development. The next thing to be considered is how to get the ladder diagram into the programmable controller. In higher order controllers, this can be accomplished through the use of dedicated personal computer software that allows the programmer to enter the ladder diagram as drawn. The software then takes care of Read the rest of this entry »

Introduction

One of the greatest strengths of using a programmable machine control, such as a PLC, is in its capability to adapt to changing conditions. When properly designed and programmed, a machine control system is able to sense that a machine is not operating at the desired or optimum conditions and can automatically make adjustments to the machine’s operating parameters so that the desired performance is maintained, even when the surrounding conditions are less than ideal. In this chapter we will discuss various methods of controlling a closed loop system and the advantages and disadvantages of each.

Simple Closed Loop Systems Read the rest of this entry »

this program compares some types normally PLC. My perpose is help someone who work in a plan and he hasn’t time to research. So he can change this program from this type PLC to another type.

ladder simulation is Pretty cool ladder simulator program for beginners from bytronic

The PLC’s from Omron can be connected to various peripheral equipment. Each device requires its own cable layout. Only the more common cables are shown here.

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Introduction

 Since most heavy machinery is mechanically powered by electric motors, the system designer must be familiar with techniques for controlling electric motors. Motor controls cover a broad range from simple on-off motor starters to sophisticated phase angle controlled dc motor controls and variable frequency ac motor drive systems. In this chapter we will investigate some of the more common and popular ways of controlling motors. Since most heavy machinery requires large horsepower ac motors, and since large single phase motors are not economical, our coverage of ac motor controls will be restricted to 3-phase systems only.   Read the rest of this entry »