1046 User Guide

Part 1: Setup

PhidgetTemperatureSensor - Select OS

PhidgetBridge

Welcome to the 1046 user guide! In order to get started, make sure you have the following hardware on hand:

• a 1046 PhidgetBridge
• a USB cable and computer
• a load cell or other sensor to connect to the 1046

Select your Operating System:

Windows

MacOS

Linux

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PhidgetBridge - Windows

Step 1: Install Phidgets Library

Step 2: Connect Devices

Step 3: Verify Connection

Step 1: Install Phidgets Library

Before you begin using your Phidgets, you will need to install the Phidget Library.

1. Download the installer for your system:

● 32-bit Installer Download

● 64-bit Installer Download

If you're unsure which one you should get, press ⊞ WIN + Pause/Break:

Before installing our libraries, be sure to read our Software License.

Step 1: Install Phidgets Library

2. Open the download. If it asks you for permission, select Run

Step 1: Install Phidgets Library

3a. Select Next

Step 1: Install Phidgets Library

3b. Read the Licence Agreement. Select Next.

Step 1: Install Phidgets Library

3c. Choose Installation Location. Select Next.

Step 1: Install Phidgets Library

3d. Confirm Install

Step 1: Install Phidgets Library

3e. Wait for Installation to complete. This should only take a few moments.

Step 1: Install Phidgets Library

3f. Installation Complete. Close installation Window.

Step 2: Connect Devices

● Connect USB Cable to your computer and PhidgetBridge

● Connect a load cell or other wheatstone bridge sensor to the PhidgetBridge

Step 3: Verify Connection

1. Open the Phidgets Control Panel:

If your Control Panel does not open, look in your taskbar. Double click the Phidget Icon.

Step 3: Verify Connection

2. If connected, your Phidgets will appear in the Phidget Control Panel.

Done!

If you're able to see and interact with your devices in the Phidget Control Panel, you're done with the Setup part of this guide.

Scroll down to Part 2: Using Your Phidget for the next step.

For more help installing in Windows (e.g. manual install, using a VM, etc.), visit this page:

● Windows Advanced Information

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PhidgetInterfaceKit 8/8/8 - MacOS

Step 1: Install Phidgets Library

Step 2: Connect Devices

Step 3: Verify Connection

Step 1: Install Phidgets Library

Before you begin using your Phidgets, you will need to install the Phidget Library.

1. Download the installer for your system:

● OS X 10.11+: Installer Download

● Mac OS X 10.7 - OS X 10.10: Installer Download

● Mac OS X 10.5 - OS X 10.6: Installer Download

Before installing our libraries, be sure to read our Software License.

Step 1: Install Phidgets Library

2. Open the download and double click on Phidgets.pkg

Step 1: Install Phidgets Library

3a. Select Continue

Step 1: Install Phidgets Library

3b. Read and continue. Read the License and click Agree.

Step 1: Install Phidgets Library

3c. Here, you have the option to select the installation location. Select Install to continue.

Step 1: Install Phidgets Library

3d. MacOS may ask for permission to install. Enter your username and password and Install Software.

Step 1: Install Phidgets Library

3e. Wait for Installation to complete. This should only take a few moments.

Step 1: Install Phidgets Library

3f. You may see a message that the extension has been blocked. Select Open Security Preferences.

Step 1: Install Phidgets Library

3g. Beside the message for Phidgets Inc, Click Allow.

Step 1: Install Phidgets Library

3h. Installation Complete, Click Close.

Step 1: Install Phidgets Library

3i. To delete the installer, click Move to Trash.

Step 2: Connect Devices

● Connect USB Cable to your computer and PhidgetBridge

● Connect a load cell or other wheatstone bridge sensor to the PhidgetBridge

Step 3: Verify Connection

1. Open the Phidgets Control Panel:

Step 3: Verify Connection

2. If connected, your Phidgets will appear in the Phidget Control Panel.

Done!

If you're able to see and interact with your devices in the Phidget Control Panel, you're done with the Setup part of this guide.

Scroll down to Part 2: Using Your Phidget for the next step.

For more info installing in MacOS (e.g. developer tools, driver extension, etc.), visit this page:

● MacOS Advanced Information

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PhidgetBridge - Linux

Step 1: Install Phidgets Library

Step 2: Connect Devices

Step 3: Verify Connection

Step 1: Install Phidgets Library

1. First, you need to install the libusb-1.0 development libraries. For example, in Debian based distributions:

apt-get install libusb-1.0-0-dev

You’ll also need a C compiler and builder, if you don’t already have one installed.

apt-get install gcc

apt-get install make

Step 1: Install Phidgets Library

2. Next, download and unpack the Phidgets library:

● libphidget22

Step 1: Install Phidgets Library

3. Use the following commands in the location you unpacked to install the library:

./configure

make

sudo make install

Step 1: Install Phidgets Library

4. (Optional) You can also download and unpack the following optional packages:

● phidget22networkserver - Phidget Network Server, which enables the use of Phidgets over your network

● phidget22admin - Admin tool to track who is connected to your Phidgets when using the network server

● libphidget22extra - Required for phidget22networkserver and phidget22admin

● libphidget22java - The Java libraries for Phidget22

For installation instructions for these packages, see the README file included with each one.

Step 2: Connect Devices

● Connect USB Cable to your computer and PhidgetBridge

● Connect a load cell or other wheatstone bridge sensor to the PhidgetBridge

Step 3: Verify Connection

1. The easiest way to verify that your libraries are working properly is to compile and run an example program. Download and unpack this C example that will detect any Phidget:

● HelloWorld C Example

Step 3: Verify Connection

2. Next, open the terminal in the location where you unpacked the example. Compile and run using:

gcc HelloWorld.c -o HelloWorld -lphidget22

sudo ./HelloWorld

ou should receive a “Hello” line for each Phidget channel that is discovered:

I don’t see any Phidgets show up in the HelloWorld example

You need to run it with sudo in order to be able to access USB devices. In order to use Phidgets without sudo, you need to set your udev rules. See the Advanced Information page on the final slide of this guide for details.

Done!

If you're able to see your devices in the Hello World example, you're done with the Setup part of this guide.

Scroll down to Part 2: Using Your Phidget for the next step.

For more info installing in Linux (e.g. Udev rules, old versions, etc.), visit this page:

● Linux Advanced Information

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Part 2: Using Your Phidget

About

The PhidgetBridge reads up to four load cells, strain gauges or Wheatstone Bridge-based sensors. The Phidget reports results as a voltage ratio. To convert from voltage ratio to a quantity like weight or force, see the Calibration Guide in the Advanced Topics section.

Explore Your Phidget Channels Using the Control Panel

You can use your Control Panel to explore your Phidget's channels.

1. Open your Control Panel, and you will find the following channels:

2. Double click on a channel to open an example program. Each channel belongs to the Voltage Ratio Input channel class:

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Voltage Ratio Input (Bridge Input): Read data from a load cell

In your Control Panel, double click on "Bridge Input":

Part 3: Create your Program

• Code Sample Generator
• Setting up your Programming Environment
• Phidget Programming Basics

Part 4: Advanced Topics and Troubleshooting

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How can I plot or record sensor data?

Note: Graphing and logging is currently only supported in the Windows version of the Phidget Control Panel.

In the Phidget Control Panel, open the channel for your device and click on the icon next to the data type that you want to plot. This will open up a new window:

If you need more complex functionality such as logging multiple sensors to the same sheet or performing calculations on the data, you'll need to write your own program. Generally this will involve addressing the correct channel, opening it, and then creating an Event Handler and adding graphing/logging code to it.

The quickest way to get started is to download some sample code for your desired programming language and then search google for logging or plotting in that language (e.g. "how to log to csv in python") and add the code to the existing change handler.

Filtering

You can perform filtering on the raw data in order to reduce noise in your graph. For more information, see the Control Panel Graphing page.

Graph Type

You can perform a transform on the incoming data to get different graph types that may provide insights into your sensor data. For more information on how to use these graph types, see the Control Panel Graphing page.

Choosing a Gain Value

We report the measured voltage in a ratiometric unit known as V/V. This is how the maximum range of sensors that use strain gauges is usually specified. V/V is the output value in V of the measured sensor, scaled for a 1V sensor supply voltage. This value will correspond to the physical quantity that the sensor is measuring, regardless of the actual voltage supplied to the sensor.

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{{UGC-Entry|Connecting Your Strain Gauge or Load Cell| | Load cells are pressure sensors that can be used with the 1046. For more information, see our Load Cell Primer.

If no documentation is available for your strain gauge, it’s possible to use a multimeter to determine how to connect it, provided there are no electronics in the sensor. First, measure resistance between the 4 wires. There are 6 combinations - two combinations will have a resistance 20-40% higher than the other four. Choose one of these high-resistance combinations, and wire it into 5V and G on the 1046. Connect the other two wires into +/-. Apply a load, if the V/V responds in the opposite way to your expectations, flip the +/- wires.

Measurement Considerations

The 1046 is designed to measure voltages as a ratio of the supply voltage - it’s not practical to make measurements of absolute voltages with this product.

For maximum accuracy, all wires from the 1046 to the sensor should be the same length and thickness. Changes in temperature will change the resistance of the wires - if they are all the same, the errors will cancel out.

Each bridge input can be powered down, reducing power consumption with 1046 sensors, and useful for reducing heating of sensors, which can introduce errors.

The number I’m getting back from the 1046 is really small

Load cells output a small voltage proportional to the amount of strain they are currently experiencing. The rated output for most load cells at full load is in the order of millivolts, so when you’re only straining the load cell at a fraction of its full load, you will get very small values. In order to convert to meaningful units like grams or newtons, you need to calibrate the load cell.

Calibration

We have observed a 1.5% difference between a 1x gain and an 8x gain. This may require that each system (1046 and sensors) be calibrated as a whole. For maximum accuracy, decide on, and keep with a chosen gain before calibrating the system.

Expensive sensors will ship with a certificate of calibration specifying, often in mv/V, how the sensor responds to stimulus. Less expensive will have to be calibrated

For an in-depth guide on calibration, see Calibrating Analog Sensors.

Measuring RTDs

Measuring Resistive Thermal Devices (RTD)

Using a Wheatstone Bridge

This diagram shows how to connect the RTD to a Wheatstone bridge, and then to a PhidgetBridge 4-Input.

A Wheatstone bridge is the classic method of measuring unknown resistances, and requires three resistors of known values. It uses the current in each leg of the bridge to create a voltage differential between both voltage dividers. Using the voltage differential and the three known resistors, the resistance of the fourth resistor can be determined.

To determine the resistance of the RTD, the following formula can be used:

$R_{RTD}={\frac {R_{3}\times [R_{2}+V_{B}\times (R_{1}+R_{2})]}{R_{1}-(R_{1}+R_{2})\times V_{B}}}$

Where $V_{B}$ is the Bridge Value given by the PhidgetBridge (in mV/V) , and $R_{1}$, $R_{2}$ and $R_{3}$ are the resistances of the known resistors.

Using a Voltage Divider

The alternate method requires only two resistors. This reduces the amount of error that can be introduced into the system due to resistor tolerances. A voltage is applied to the two resistors and the RTD in series. The voltage drop across the RTD is measured. Using the voltage drop and the values of the two resistors, the resistance of the RTD can be determined.

This diagram illustrates how to connect the RTD to the PhidgetBridge with a voltage divider cirtuit.

To determine the resistance of the RTD, the following formula can be used:

$R_{RTD}=(R_{1}+R_{2})\times {\frac {V_{B}}{1-V_{B}}}$

Where $V_{B}$ is the Bridge Value given by the PhidgetBridge (in mV/V) , and $R_{1}$ and $R_{2}$ are the resistances of the known resistors.

Getting Higher Accuracy

In order to get the highest accuracy from the RTD, consider the following:

• Use resistors with a high degree of tolerance. There will be less variability in the manufacturing of 0.1% resistors when compared to 1% resistors.
• Measure the known resistors with an ohmmeter. By obtaining the most accurate measurements for the known resistances, the formula will result in a more accurate measurement of the RTD.
• Use a moving average when obtaining the Bridge Value to reduce the amount of noise in the measured signal.
• Estimate or Measure the resistance of the +5V and GND wires between the RTD and the 1046 PhidgetBridge. Add this resistance to the two resistors.
• Turn off the power to the RTD (by disabling the channel on the PhidgetBridge) to reduce self-heating of the RTD.
• By using higher resistor values (> 1 Kilo ohm), there will be less self-heating of the RTD, but the resolution of the measurement will be reduced somewhat. We recommend 1 Kilo Ohm resistors as a reasonable trade off.

Setting the Change Trigger and Data Interval

The Change Trigger is the minimum change in the sensor data needed to trigger a new data event.

The Data Interval is the time (in ms) between data events sent out from your Phidget.

The Data Rate is the reciprocal of Data Interval (measured in Hz), and setting it will set the reciprocal value for Data Interval and vice-versa.

You can modify one or both of these values to achieve different data outputs. You can learn more about these properties here.

How do I know what channel, serial number, or hub port to use in my program?

Before you open a Phidget channel in your program, you can set these properties to specify which channel to open. You can find this information through the Control Panel.

1. Open the Control Panel and double-click on the red map pin icon:

2. The Addressing Information window will open. Here you will find all the information you need to address your Phidget in your program.

See the Phidget22 API for your language to determine exact syntax for each property.