Serial driver for S7-300/400 PLCs using MPI protocol

Tue, 19 Jan 2010 01:07:00 GMT

We have included a new driver to communicate with Siemens S7-300/400 PLCs using MPI protocol through a serial communication. Now you can create low cost applications where it is required to read and/or write MW registers, among other type of data.

You can see more information about this driver here: http://www.cpksoft.com/Drivers/tabid/55/ProductID/125/Default.aspx

Or yopu can also download the manual in pdf format here: http://www.cpksoft.com/Files/Manuals/Pdf/XS7MPI.pdf

Driver for Emerson Daniel DanLoad 6000 Electronic Preset

Tue, 12 Aug 2008 14:19:00 GMT

A new driver for the Emerson Daniel DanLoad 6000 Electronic Preset is now available and is part of the drivers included with each unlimited license of TAS-HMITalk.

The driver supports the following commands:

Start Communications
Request Meter Values
Authorize Transaction
Configure Recipe
Authorize Batch
Start Batch
Stop Batch
End Batch
Batch Data By Component
End Transaction
Transaction Data by Component
Request Status
Clear Status
Change Operating Mode
Display Message
Clear Display
Read Input
Write Output
Reset Primary Alarms

The complete manual in pdf format can be downloaded here.

What is SCADA?

Thu, 26 Jun 2008 18:28:00 GMT

Introduction

SCADA or Supervisory Control And Data Acquisition is a large scale control system for automated industrial processes like municipal water supplies, power generation, steel manufacturing, gas and oil pipelines etc. SCADA also has applications in large scale experimental facilities like those used in nuclear fusion.

SCADA systems monitor and control these operations by gathering data from sensors at the facility or remote station and then sending it to a central computer system that manages the operations using this information.

The SCADA System

The sheer size and of the operations we saw earlier demands that the control system be equally elaborate to handle the requirements. This is where SCADA scores. The SCADA system is equipped to manage anything from a few thousands to a million input/output channels. The technology is still evolving and we can expect an expansion of the market for SCADA.

A full fledged SCADA system is made up of signal hardware for input/ output, networks, control equipment, user interface (sometimes called the Human-Machine Interface or HMI), communication equipment and the software to go with it all. And here we are talking about the central command system of SCADA. The central system is often miles away from where the operations take place. Thus the system also needs on-site sensors to collect and monitor data.

How SCADA Works

The measurement and control system of SCADA has one master terminal unit (MTU) which could be called the brain of the system and one or more remote terminal units (RTU). The RTUs gather the data locally and send them to the MTU which then issues suitable commands to be executed on site. A system of either standard or customized software is used to collate, interpret and manage the data.

SCADA as of now uses predominantly open-loop control systems, though some closed-loop characteristics are often built in. As this is an open-loop system, it means that SCADA system cannot use feedback to check what results its inputs have produced. In other words, there is no machine-learning.

SCADA and Other Control Systems

There are several other systems that are used for similar purposes as SCADA. These are generally called Distributed Control Systems (DCS). The functions are the same; the difference is in the range. Distributed Control Systems are typically effective within a confined area like a factory complex. Thus the communication is carried out through a local area network (LAN). These networks are highly dependable and fast, and can manage closed-loop (feedback based) control.

DCS networks have their limitations. They cannot cover large territories. This is where SCADA comes in handy. However the communication systems are not as reliable as a LAN, and therefore it is not viable to implement closed-loop control. Right now, the size and scope is what mark SCADA.

This article was taken from http://www.roseindia.net/technology/scada/what-is-SCADA.shtml

Visual Basic and SCADA

Thu, 19 Jun 2008 15:30:00 GMT

Posted by Ed McClure on 15 January, 2007 - 6:10 pm

VB is an one option for programming a SCADA or HMI application. Others include "canned" software designed specifically for SCADA and HMI application. Examples of canned packages would be Rockwell Software's RSView and Wonderware. There are pro's and con's to both VB and canned SCADA/HMI packages.

VB Pro's:

1. No runtime licenses (cheaper)
2. More flexible

Generally with VB you would purchase a third party ActiveX control to facilitate PLC communication. There would be an additional cost for that control, but again once you purchase is (under $1,000) there are no runtime fees for any applications you develop with it. Also, there are many third party graphics packages aimed specifically at the industrial control market. These add-ons can greatly improve the look and reduce the development cost of your application.

VB Con's:

1. In general the code is more difficult (more involved) to write and requires higher level code skills for the customer to maintain and modify. The time from concept to finished application will almost always be longer with VB.

Canned Package Pro's:

1. Quicker application development.
2. PLC communication generally built in
3. Library of standard SCADA/HMI controls (buttons, dials, sliders, etc. built in.

Canned Package Con's:

1. These packages can be fairly expensive and you generally incurr additional runtime cost for each application which must me licensed to the customer.
2. Less flexibility in how you build the application.

The bottom line on which package is right for you would be the choice application and market. Many industrial customers want to use HMI pacakages that they already support in-house. If you are an OEM there is a lot of money to be saved in runtime fees if you take the hit for the development time up front.

This article was posted as "VB and SCADA" at Control.com and can be found at: http://www.control.com/thread/1026230388

Recent News

Serial driver for S7-300/400 PLCs using MPI protocol

Driver for Emerson Daniel DanLoad 6000 Electronic Preset

What is SCADA?

Visual Basic and SCADA