1122 User Guide

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Getting Started

Checking the Contents

You should have received: A 30A current sensor AC/DC A sensor cable		In order to test your new Phidget you will also need: A PhidgetInterfaceKit 8/8/8 or PhidgetTextLCD A USB cable

Connecting the Pieces

Connect the 30 Amp Current Sensor AC/DC to the Analog Input 6 on the PhidgetInterfaceKit 8/8/8 using the sensor cable. To measure alternating current, you can use the DC port to measure a peak-to-peak AC signal, or you can use the AC port to measure the RMS value. To measure direct current, either the AC port or the DC port will work, since RMS calculations will have no effect on a DC signal. Connect your power source to the terminal block. Connect the PhidgetInterfaceKit to your PC using the USB cable.

Testing Using Windows 2000 / XP / Vista / 7

Make sure you have the current version of the Phidget library installed on your PC. If you don't, follow these steps:

1. Go to the Quick Downloads section on the Windows page
2. Download and run the Phidget21 Installer (32-bit, or 64-bit, depending on your system)
3. You should see the icon on the right hand corner of the Task Bar.

Running Phidgets Sample Program

Double clicking on the icon loads the Phidget Control Panel; we will use this program to ensure that your new Phidget works properly.

The source code for the InterfaceKit-full sample program can be found in the quick downloads section on the C# Language Page. If you'd like to see examples in other languages, you can visit our Languages page.

Updating Device Firmware

If an entry in this list is red, it means the firmware for that device is out of date. Double click on the entry to be given the option of updating the firmware. If you choose not to update the firmware, you can still run the example for that device after refusing.

Double Click on the icon to activate the Phidget Control Panel and make sure that the Phidget InterfaceKit 8/8/8 is properly attached to your PC.
Double Click on Phidget InterfaceKit 8/8/8 in the Phidget Control Panel to bring up InterfaceKit-full and check that the box labelled Attached contains the word True. Make sure that the Ratiometric box is Ticked. The Amp value of your power source is displayed in the Analog In box. If you do not connect any power source to the sensor board, the Analog In value should be 500 if you use the DC connector and 0 if you use the AC connector. You can adjust the input sensitivity by moving the slider pointer. Click on the Sensors button to bring up the Advanced Sensor Form.
In the Sensor 6 box, select the 1122 - 30Amp Current Sensor [DC] or [AC] from the drop down menu. The current measured across the sensor is shown here. Formula used to convert the analog input SensorValue into current.

Testing Using Mac OS X

1. Go to the Quick Downloads section on the Mac OS X page
2. Download and run the Phidget OS X Installer
3. Click on System Preferences >> Phidgets (under Other) to activate the Preference Pane
4. Make sure that the is properly attached.
5. Double Click on in the Phidget Preference Pane to bring up the Sample program. This program will function in a similar way as the Windows version.

Using Linux

For a step-by-step guide on getting Phidgets running on Linux, check the Linux page.

Using Windows Mobile / CE 5.0 / CE 6.0

For a step-by-step guide on getting Phidgets running on Windows CE, check the Windows CE page.

Technical Details

The 30 Amp Sensor measures alternating current (AC) up to 30 Amps and direct current (DC) between –30 and +30 Amps. It uses a hall-effect based sensor to measure the magnetic field induced by the applied current flowing through a copper conductor. It then converts the magnetic data into a current measurement with internal calculations. The AC output will give the RMS (Root Mean Square) value of an alternating current assuming the current is sinusoidal, and the sine wave is varying equally across the zero point. The AC output can also be used for signals that are not varying evenly around the zero point but the value will be the RMS plus a DC component. If a DC signal is being measured, the AC output will produce a signal that can be used to calculate the current but without the value representing direction of current flow.

Measuring Current

The Phidgets Current Sensor should be wired in series with the circuit under test, as shown in the following diagrams.

In the diagrams above, the voltage source is represented by the battery symbol. The load is represented by a light bulb or schematic resistor symbol. The current flowing from the battery to the load is measured through the current sensor.

Formulas

The formula to translate SensorValue into Current is:

${\text{DC Current (A)}}={\frac {\text{SensorValue}}{13.2}}-37.8787$

${\text{AC Current (RMS)}}={\text{SensorValue}}\times 0.04204$

Other Interfacing Alternatives

If you want maximum accuracy, you can use the RawSensorValue property from the PhidgetInterfaceKit. To adjust a formula, substitute (SensorValue) with (RawSensorValue / 4.095) If the sensor is being interfaced to your own Analog to Digital Converter and not a Phidget device, our formulas can be modified by replacing (SensorValue) with (Vin * 200). It is important to consider the voltage reference and input voltage range of your ADC for full accuracy and range.

Each Analog Input uses a 3-pin, 0.100 inch pitch locking connector. Pictured here is a plug with the connections labelled. The connectors are commonly available - refer to the Analog Input Primer for manufacturer part numbers.

API

Phidget analog sensors do not have their own API- they simply output a voltage that is converted to a digital value and accessed through the "Sensor" properties and events on the PhidgetInterfaceKit API. It is not possible to programmatically identify which sensor is attached to the Analog Input. To an InterfaceKit, every sensor looks the same. Your application will need to apply formulas from this manual to the SensorValue (an integer that ranges from 0 to 1000) to convert it into the units of the quantity being measured. For example, this is how you would use a temperature sensor in a C# program:

 // set up the interfacekit object
InterfaceKit IFK = new InterfaceKit();

// link the new interfacekit object to the connected board
IFK.open("localhost", 5001);

// Get sensorvalue from analog input zero
int sensorvalue = IFK.sensors[0].Value;

// Convert sensorvalue into temperature in degrees Celsius
double roomtemp = Math.Round(((sensorvalue * 0.22222) - 61.11), 1);

See the PhidgetInterfaceKit User Guide for more information on the API and a description of our architecture.

For more code samples, find your preferred language on the Languages page.

Product History

Date	Board Revision	Device Version	Comment
March 2008	0	N/A	Product Release