software feed back for PLC

The product offering has been simplified to a full support PC-DSOFT5 package that programs all of our DirectLOGIC PLCs.
And, we've introduced our new PC-DS100 package, which is a full-featured FREE programming package with a 100 word limitation.
(PC-DS100 is only available by download from our Web site).
DirectSOFT5™- DirectLOGIC PLC Programming Software Overview


PC-DS100 is our all new FREE full-featured software package that allows a maximum of 100 words for programming, editing, and downloading in any Koyo DirectLOGIC CPU. A perfect solution for small applications! Larger programs can be created and saved but NOT reopened or downloaded without upgrading to the full version. Download PC-DS100 at no charge now. ... Free! 

download pdf file and read it... 

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Control panel with a PLC controller

With invention of programmable controllers, much has changed in how an process control system is designed. Many advantages appeared. Typical example of control panel with a PLC controller is given in the following picture.

Advantages of control panel that is based on a PLC controller can be presented in few basic points:

1. Compared to a conventional process control system, number of wires needed for connections is reduced by 80%
2. Consumption is greatly reduced because a PLC consumes less than a bunch of relays
3. Diagnostic functions of a PLC controller allow for fast and easy error detection.
4. Change in operating sequence or application of a PLC controller to a different operating process can easily be accomplished by replacing a program through a console or using a PC software (not requiring changes in wiring, unless addition of some input or output device is required).
5. Needs fewer spare parts
6. It is much cheaper compared to a conventional system, especially in cases where a large number of I/O instruments are needed and when operational functions are complex.
7. Reliability of a PLC is greater than that of an electro-mechanical relay or a timer.

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PLC detail

What is a PLC?

 PLC, is more or less a small computer with a built-in operating system (OS). This OS is highly specialized to handle incoming events in real time, i.e. at the time of their occurrence.
The PLC has input lines where sensors are connected to notify upon events (e.g. temperature above/below a certain level, liquid level reached, etc.), and output lines to signal any reaction to the incoming events (e.g. start an engine, open/close a valve, etc.).
The system is user programmable. It uses a language called "Relay Ladder" or RLL (Relay Ladder Logic). The name of this language implies that the control logic of the earlier days, which was built from relays, is being simulated.

The PLC's purpose in life

The PLC is primarily used to control machinery. A program is written for the PLC which turns on and off outputs based on input conditions and the internal program. In this aspect, a PLC is similar to a computer. However, a PLC is designed to be programmed once, and run repeatedly as needed. In fact, a crafty programmer could use a PLC to control not only simple devices such as a garage door opener, but their whole house, including switching lights on and off at certain times, monitoring a custom built security system, etc.
Most commonly, a PLC is found inside of a machine in an industrial environment. A PLC can run an automatic machine for years with little human intervention. They are designed to withstand most harsh environments.

History of PLCs

When the first electronic machine controls were designed, they used relays to control the machine logic (i.e. press "Start" to start the machine and press "Stop" to stop the machine). A basic machine might need a wall covered in relays to control all of its functions. There are a few limitations to this type of control.

• Relays fail.
• The delay when the relay turns on/off.
• There is an entire wall of relays to design/wire/troubleshoot.

A PLC overcomes these limitations, it is a machine controlled operation.

Recent developments

PLCs are becoming more and more intelligent. In recent years PLCs have been integrated into electrical networks i.e. all the PLCs in an industrial environment have been plugged into a network which is usually hierarchically organized. The PLCs are then supervised by a control center. There exist many proprietary types of networks. One type which is widely known is SCADA (Supervisory Control and Data Acquisition).

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