Posts Tagged ‘SCADA’

A Brief Description of SCADA System Signals

Sunday, June 19th, 2011

It has been a while, I left this site without any updates. So, here I present a basic of a SCADA system signal. It’s basic and have to describe it a way earlier but, left out with an assumption every SCADA engineer should have known it. Anyway, as a general reading, this topic should be one of important information for public readers.

basic circuit of instrument signal tappingThe most common current signal standard in modern use is the 4 to 20 milliamp (4-20 mA) loop, with 4 milliamps representing 0 percent of measurement, 20 milliamps representing 100 percent, 12 milliamps representing 50 percent, and so on. The use of a 4 mA reading to indicate zero is known as “live zero.” This helps to distinguish a zero reading from a “dead signal” or non-functioning equipment. The range of readings possible for a properly functioning system then is only 16 mA (20 mA – 4 mA). This 16 mA range is known as the “live signal.” The actual reading being recorded in mA is called the “process variable.” The PV indicates a percentage of a particular measurement being monitored. The table below shows the relationship between various PVs and their corresponding percentages.

signal comparison tableA convenient feature of the 4-20 mA standard is the ease in converting these signals to 1-5 volt indicating instruments, as the table on the left shows. A simple 250-ohm precision resistor connected in series with the circuit will produce arange of readings from 1 volt of drop at 4 milliamps to 5 volts of drop at 20 milliamps. The current loop scale of 4-20 milliamps has not always been the standard for currentinstruments. In the past, 10-50 milliamp signals were used more frequently. That standard has since become obsolete. The main reason for the eventual supremacy of the 4-20 milliamp loop was safety. Lower circuit voltages and lower current levels (compared to 10-50 mA systems) mean less chance for electrical shock injuries and/or the generation of sparks capable of igniting flammable environments in certain industrial applications.

An Overview of  SCADA Signal Calculations

Definition of terms

Dead signal: A reading from a non-functioning system that can be mistaken for a measurement.
Live signal:
The range of possible process variables. In a 4 – 20 mA system, any signal below 4 mA or above 20 mA indicates malfunctioning equipment. The range of useable signals is between 4 & 20 mA. Therefore, the live signal = 16 mA.
Live zero:
A reading other than zero used to indicate zero so that a zero reading can be distinguished from a dead signal. In 4 – 20 mA systems, the live zero = 4 mA.
Process variable. The signal reading, in mA, that represents a percentage of a particular measurement.

One of the more common uses for SCADA systems is the monitoring of storage levels. Formulas for making these calculations include:

mA to feet conversion

So, given a SWH of 30 ft, and board reading of 14.67 mA, the water level would be calculated as follows:

water level calculation

Kindly, do enjoy to use or share this information. Have a nice day.

Reference: Water Opcert School

Save sensor data to Google Spreadsheets by Codebox

Saturday, December 25th, 2010

I found this is really a good way to gather data, since Google Spreadsheets is free and can be accessed from any places in the world as long as connected to the internet. Plus, you can share it with selected persons you want. It’s quite useful for scientific researchers to share and analyze their findings. Check this out (completed with the codes):

The “Hello Arduino” section in Chapter 11 of Getting Started with Processing shows how to read data into Processing from Arduino. In a nutshell, the Arduino code (example 11-6 in the book) reads data from a light sensor and writes it out to the serial port. The section then goes on to describe a number of increasingly sophisticated sketches that retrieve and visualize the sensor data using Processing’s Serial library.

This Codebox shows you how to save this sensor data to a Google Spreadsheet. The cool thing is that you can then use any of the goodies that Google provides (charts, gadgets, maps, etc) directly with your data. While the light sensor is pretty basic, you can use this basic setup to record data from more sophisticated sensors, such as a Parallax GPS receiver module into Google Spreadsheets, and then create a map of where you’ve been that you could post as a gadget.

The sketch relies on the Google API Client Library for Java, which is a set of code libraries for interacting with various Google’s services (not just Spreadsheets). In researching this article, I found Processing guru Jer Thorpe‘s article Open Science, H1N1, Processing, and the Google Spreadsheet API a great inspiration. While it’s based on an older version of the API (version 1.0, while the APIs are now up to version 3.0), it’s a great introduction to interacting with Google.

Courtesy Make

GardenBot Is Monitoring Your Garden

Sunday, November 28th, 2010

how-to_module-map courtesy of

Amazing work, and very interesting solution (of an experience of nature-lovers and DIYers) to keep an eye on your garden:

GardenBot is a garden monitoring system. This means that you put sensors in your garden, and GardenBot will show you charts of the conditions in your garden — so you can see the world the way your plants see it.

I did… er, I mean hi. My name is Andrew Frueh. Me and my wife, Melissa, like to garden a lot. We’re always experimenting with different methods in our garden and compost. We already were using a soaker hose for our garden. Last year, we used one of those mechanical timers to turn the soaker on for a pre-determined amount of time. But then…
I discovered Arduino, and immediately became engrossed. Arduino is a little computer (called a microcontroller) about the size of a business card. It has a bunch of analog and digital inputs/outputs so you can hook up various sensors, buttons, switches, audio/video devices — it’s pretty friggin’ cool. See the parts page for more information.
Anyway, considering my interests, I thought “gee, it sure would be neat to use the Arduino board to control the watering in the garden”. But then one thing led to another… and now we get to the (somewhat complete) GardenBot system that you have before you.
Like a lot of DIY-ers, I am entirely self-trained. So, there are a lot of holes in my knowledge. As I hunted around for information on the web, I found that too often the information in various tutorials was written by someone who failed to remember that lay-people (incidentally the target audience for any tutorial) don’t know the jargon, and therefor can have great difficulty in decoding the information. One of my goals with this project, is to have all the pieces laid out in plain language — step by step — to walk you through the whole process. Hopefully I pull that off.

check out the web, as all the resources and methods are well documented. Good job!


Brilliant SCADA System that failed

Sunday, September 19th, 2010

A friend of mine shared an article about software failures. it’s a good stuff to read, where we can avoid some mistakes that previously been made by software developers. there is a SCADA software there – some of the problems that I’ve been encountered too in my life. check this out: – a monitoring application for water supply companies. It was a complex client server application that would receive monitoring data from specialized hardware and store that data inside a SQL database. The client displays that data in different graphs, provides printable reports or sends alarm messages via SMS if a monitored value is not within its specified limits. I developed Net-Herald as a perfect fit for that specialized hardware that is provided by a local manufacturer. That way, so I hoped, I could profit from their sales leads and would find a smoother way into these water supply companies. The downside of course, was that my software would only work with their hardware. (more…)

Arad Metering Technologies Conserves Water via Battery-Operated Drones

Sunday, August 22nd, 2010

remote meter reader
Illustration by Chris Philpot

The word drone may sounds related to any contemporary sci-fi flicks, or images of attacks carried out remotely on hostile lands, or even your high-school biology teacher’s voice. We don’t expect a drone to help us save water, but that’s what Arad Metering Technologies intends to do. The Israeli company’s battery-operated drone is one of the novel tools it’s deploying to help consumers and companies conserve H2O — and to make money.

Such an idea would come out of Israel is no coincidence. The country is poor in water and rich in tech innovation, much of it born of constant military conflict. Israel pioneered the use of unmanned aerial vehicles after it lost many fighter jets in the 1973 war. But Arad’s drones don’t fight: They read data from the company’s patented water-meter system to detect leakage or, in irrigation systems, drought.

The World Bank estimates that water wastage costs utilities $14 billion a year worldwide; in developing countries, 200 million more people could be served by the water lost to leaks and theft. Arad CEO Dan Winter says this is largely a consequence of how the business works in places where water is cheap or untaxed: “You train people to abuse water because they pay very little.”

Photos courtesy of Arad Technologies LTD

With this innovation, instead of meter reading – it can provide real time monitoring of water supply infrastructures. Its technology can find irregularities — a pipe failure, an unusually low flow rate, or a too-constant one that could indicate a leak — in a few hours, rather than every 60 days as with a typical meter reading.

Arad’s system is built around what looks like a standard meter. The difference is on the inside, where you’ll find 3G wireless technology, a microcontroller, and 20-year batteries. Every 11 to 30 seconds, the system transmits data, which can be picked up by a drone (best for quickly covering big distances in remote areas) or by a drive-by or fixed-base reader. The data are then analyzed by computer to gauge how much water has been consumed, how much was lost, and even where tampering may have taken place. As a result, companies can save both water and man hours.

The possibilities for Arad’s services go far beyond water should be covering abilities to monitor everything from municipal infrastructure, such as traffic lights, to security-camera networks — basically any complex system prone to localized failures and waste. Arad has its own way, to proof drones could be associated with saving, not destroying; life, not death.

Courtersy: Tree Hugger, Fast Company

Flood Triggered Automated Camera System (FTACS)

Tuesday, April 6th, 2010


When the Department of Natural Resources of Australia decided that they needed to capture data about the natural flooding of a cave, they turned to a hacker to get results. The goal was to photograph the area during these floods with an automated system. In the end, they used a gutted Lumix digital camera mounted in a trash can, covered in aluminium foil. Though it sounds a bit silly, the final product turned out quite nice. You can see the build log, schematics, and results on the project page.

In this case the event they are trying to capture pictures of a cave flood with a Flood Triggered Automated Camera System. The system consists of a camera that is connected to a moisture sensor so that the a camera can start taking pictures when the sensor gets wet. Pictures will continue to be taken every 15 minutes until the moisture levels go back to normal. Since it is being installed in a remote location it needed to be self sustaining.

The water sensor is an interesting design since it has the ability of killing the power to the entire system when the conditions are dry. This is done by using a Darlington transistor feeding a relay.

Courtesy of Penguins Lab

Logging weight changes

Saturday, August 15th, 2009


This is a classic example of a well done hack, simply for the sake of hacking. [Jorge] wanted to be able to chart his weight changes.  His solution wasn’t to simply buy a scale that could be hooked to the computer. Those are available and aren’t really that expensive. He could have even used pencil and paper to chart it in a few seconds. Instead, [Jorge] started hacking. He took apart a digital scale he already had and installed his own circuit to display weight and write the values to a CSV. The CSV resides on a removable card which can then be put in his computer to chart the data in openoffice.

source: Hack A Day

DataNet Wireless Data Acquisition System

Friday, December 26th, 2008

The DataNet is a professional wireless data acquisition system using the Zigbee wireless protocol. Consisting of a USB base station, DataNet acquisition units, repeater units and the DataNet PC Suite logging software. The acquisition units have 4 inputs for direct measurement of PT-100, thermocouple, voltage 4-20mA, frequency and pulse. There is also a version with the addition of built-in temperature and humidity sensors.

Source: Audon Electronics

RTU enables Modbus control over Ethernet

Wednesday, November 19th, 2008

Audon Electronics is offering the Edam-9000 range of Ethernet-based industrial data acquisition and control RTU devices.

The Edam-9000 range is based on 10/100 Ethernet networking standards and supports the Modus/TCP protocol.

The Edam-9000 also supports UDP protocol over Ethernet networking.

There are six models in the range, covering voltage, thermocouple and PRT analogue inputs, digital inputs, pulse counting and transistor outputs.

All have a 10-30VDC power supply range, full opto-isolation and are housed in robust DIN rail mount enclosures.

Users can add Edam-9000 I/O modules to existing Ethernet networks or use Edam-9000 modules in new or existing SCADA systems.

source: Processing Talks

Yokogawa releases advanced data recorder

Sunday, November 9th, 2008

Yokogawa Electric has released the DXadvanced R3 data acquisition and display station for networks.

The product is an enhanced version of the Daqstation series of paperless recorders designed for more efficient monitoring of production lines.

The DXadvanced has a built-in panel and offers integrated display, recording and communication functions.