Power Guards
Introduction to Phidget Power Guards
Products for USB Sensing and Control
The Power Guard Phidget is designed to protect your hardware by detecting and preventing overvoltage situations. This board is designed for high current systems and is capable of protecting your equipment from even the largest of power spikes. If communication between this board and the computer is interrupted, it will continue to power the device and protect against the last chosen overvoltage trigger. This Phidget connects to your computer through a VINT Hub.
This Phidget is a smart device that must be controlled by a VINT Hub. For more information about VINT, have a look at the VINT Overview page. You can use a Phidget Cable to simply and easily connect the two devices. Here's a list of all of the different VINT Hubs currently available:
| Product | Board Properties | |||
|---|---|---|---|---|
| Part Number | Price | Number of VINT Ports | VINT Communication Speed Max | Controlled By |
 VINT Hub Phidget
|
$40.00 | 6 | 1 Mbit/s | USB (Mini-USB) |
 1-Port VINT Hub Phidget
|
$24.00 | 1 | 1 Mbit/s | USB (USB-A) |
 VINT Hub Phidget
|
$35.00 | 6 | 1 Mbit/s | USB (Mini-USB) |
 VINT Hub Phidget
|
$30.00 | 6 | 100 kbit/s | USB (Mini-USB) |
 Wireless VINT Hub
|
$60.00 | 6 | 100 kbit/s | Local Network (Ethernet or Wi-Fi) |
 PhidgetSBC4
|
$120.00 | 6 | 100 kbit/s | — |
Use a Phidget cable to connect this device to the hub. You can solder multiple cables together in order to make even longer Phidget cables, but you should be aware of the effects of having long wires in your system.
| Product | Physical Properties | |
|---|---|---|
| Part Number | Price | Cable Length |
 Phidget Cable 10cm
|
$1.50 | 100 mm |
 Phidget Cable 30cm
|
$1.75 | 300 mm |
 Phidget Cable 60cm
|
$2.00 | 600 mm |
 Phidget Cable 60cm
|
$2.00 | 600 mm |
 Phidget Cable 90cm
|
$2.00 | 900 mm |
 Phidget Cable 120cm
|
$2.25 | 1.2 m |
 Phidget Cable 150cm
|
$2.50 | 1.5 m |
 Phidget Cable 180cm
|
$2.75 | 1.8 m |
 Phidget Cable 350cm
|
$3.00 | 3.5 m |
 Phidget Cable Kit
|
$10.00 | 80 mm |
This Phidget protects a power supply between 8 and 30V DC. Check the product page or data sheet of the device being powered to determine how much current is needed and what voltage range is permissable. Select the power supply from the list below that matches your region's wall socket type.
| Product | Electrical Properties | Physical Properties | ||
|---|---|---|---|---|
| Part Number | Price | Power Supply Current | Output Voltage | Wall Plug Style |
 Power Supply 24VDC 14.6A
|
$40.00 | 14.6 A | 24 V | — |
 Power Supply 24VDC 25A Current Limiting
|
$120.00 | 25 A | 24 V | — |
 Power Supply DIN Mount 24VDC 1A
|
$20.00 | 1 A | 24 V | — |
 Power Supply 12VDC 0.5A - EU
|
$1.50 | 500 mA | 12 V | European |
 Power Supply 12VDC 0.5A - US
|
$1.50 | 500 mA | 12 V | North American |
 Power Supply 12VDC 2.0A - AU
|
$10.00 | 2 A | 12 V | Australian |
 Power Supply 12VDC 2.0A - EU
|
$10.00 | 2 A | 12 V | European |
 Power Supply 12VDC 2.0A - UK
|
$10.00 | 2 A | 12 V | British |
 Power Supply 12VDC 5A
|
$20.00 | 5 A | 12 V | — |
 Power Supply 24VDC 1.0A - US
|
$10.00 | 1 A | 24 V | North American |
 Power Supply 24VDC 2.5A
|
$20.00 | 2.5 A | 24 V | — |
 Power Supply 24VDC 5A
|
$40.00 | 5 A | 24 V | — |
 Power Supply-12VDC 2.0A - US
|
$10.00 | 2 A | 12 V | North American |
The Power Guard Phidget is designed to protect your hardware by detecting and preventing overvoltage and over-temperature situations. If the voltage or temperature exceeds the thresholds chosen in your program, it will automatically cut power. You can re-enable power via software when you’ve determined that conditions are safe to do so.
Connect your power supply to the VIN and GND terminals, and the power lines for the rest of the system to the OUT and GND terminals, like in the picture above.
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 a different channel class:
In your Control Panel, double click on "Power Supply Protector":
In your Control Panel, double click on "Temperature Sensor":
In your Control Panel, double click on "Voltage Sensor":
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.
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.
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.
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.
Firmware Upgrade
MacOS users can upgrade device firmware by double-clicking the device row in the Phidget Control Panel.
Linux users can upgrade via the phidget22admin tool (see included readme for instructions).
Windows users can upgrade the firmware for this device using the Phidget Control Panel as shown below.
Firmware Downgrade
Firmware upgrades include important bug fixes and performance improvements, but there are some situations where you may want to revert to an old version of the firmware (for instance, when an application you're using is compiled using an older version of phidget22 that doesn't recognize the new firmware).
MacOS and Linux users can downgrade using the phidget22admin tool in the terminal (see included readme for instructions).
Windows users can downgrade directly from the Phidget Control Panel if they have driver version 1.9.20220112 or newer:
Firmware Version Numbering Schema
Phidgets device firmware is represented by a 3-digit number. For firmware patch notes, see the device history section on the Specifications tab on your device's product page.
Starting from firmware version 110, using Phidget22 library versions 1.0.0.20190107 and later, this device supports the use of a failsafe feature to put your device in a safe state should your program hang or crash.
With this feature, the PowerGuard channel on this device has a settable failsafe timer.
If the failsafe is not enabled, the device will behave as it did before the addition of this feature, maintaining the last state it received until it is explicitly told to stop.
Enabling the failsafe feature for a channel starts a recurring failsafe timer. Once the failsafe timer is enabled, it must be reset within the specified time or the channel will enter a failsafe state. Resetting the failsafe timer will reload the timer with the specified failsafe time, starting when the message to reset the timer is received by the Phidget.
For example: if the failsafe is enabled with a failsafe time of 1000ms, you will have 1000ms to reset the failsafe timer. Every time the failsafe timer is reset, you will have 1000ms from that time to reset the failsafe again.
If the failsafe timer is not reset before it runs out, the channel will enter a failsafe state. For PowerGuard channels, this will disable the power output. Once the channel enters the failsafe state, it will reject any further input until the channel is reopened.
To prevent the channel from falsely entering the failsafe state, we recommend resetting the failsafe timer as frequently as is practical for your applicaiton. A good rule of thumb is to not let more than a third of the failsafe time pass before resetting the timer.
Once the failsafe has been enabled, it cannot be disabled by any means other than closing and reopening the channel.
When you use a failsafe in your program, we strongly recommend setting up an error event handler to catch the Failsafe Error Event, to allow your program to catch the failsafe event.
If you want your program to try to automatically recover from a failsafe state, you can close and re-open the channel from the error event handler after determining a failsafe condition caused the event.
| Board Properties | |
|---|---|
| Controlled By | VINT |
| Power Supply Protector | |
| Trip Voltage | Selectable via software 8 - 33 VDC |
| Continuous Current | 50 A |
| Overtemperature Trigger | 125 °C |
| Sampling Interval Min | 100 ms/sample |
| Sampling Interval Max | 60 s/sample |
| Fan Trigger | 75 °C |
| Electrical Properties | |
| Current Consumption Min (VINT Port) | 100 μA |
| Supply Voltage Min | 8 V DC |
| Supply Voltage Max | 30 V DC |
| Power Consumption | 250 mW |
| Isolation Voltage (DC) | 5 kV DC |
| Physical Properties | |
| Recommended Wire Size | 6 - 14 AWG |
| Operating Temperature Min | -40 °C |
| Operating Temperature Max | 85 °C |
| Customs Information | |
| Canadian HS Export Code | 8471.80.00 |
| American HTS Import Code | 8471.80.40.00 |
| Country of Origin | CN (China) |
| Date | Board Revision | Device Version | Comment |
|---|---|---|---|
| August 2017 | 0 | 101 | Product Release |
| January 2018 | 0 | 102 | Increased change trigger limit from 25V to 32V |
| May 2019 | 0 | 110 | Added failsafe timer functionality |
| May 2023 | 0 | 120 | Failsafe now resets from any successful packet being sent |
| Channel Name | API | Channel |
|---|---|---|
| Power Supply Protector | PowerGuard | 0 |
| Voltage Sensor | VoltageInput | 0 |
| Temperature Sensor | TemperatureSensor | 0 |
| API | Detail | Language | OS | |
|---|---|---|---|---|
| PowerGuard | Visual Studio GUI | C# | Windows | Download |
| PowerGuard | JavaScript | Browser | Download | |
| PowerGuard | Objective-C | macOS | Download | |
| PowerGuard | Swift | macOS | Download | |
| PowerGuard | Swift | iOS | Download | |
| PowerGuard | Visual Basic .NET | Windows | Download | |
| PowerGuard | Max/MSP | Multiple | Download | |
| VoltageInput | Visual Studio GUI | C# | Windows | Download |
| VoltageInput | Multi-Channel Example | JavaScript | Browser | Download |
| VoltageInput | JavaScript | Browser | Download | |
| VoltageInput | Objective-C | macOS | Download | |
| VoltageInput | Swift | macOS | Download | |
| VoltageInput | Swift | iOS | Download | |
| VoltageInput | Visual Basic .NET | Windows | Download | |
| VoltageInput | Max/MSP | Multiple | Download | |
| TemperatureSensor | Visual Studio GUI | C# | Windows | Download |
| TemperatureSensor | JavaScript | Browser | Download | |
| TemperatureSensor | Objective-C | macOS | Download | |
| TemperatureSensor | Swift | macOS | Download | |
| TemperatureSensor | Swift | iOS | Download | |
| TemperatureSensor | Visual Basic .NET | Windows | Download | |
| TemperatureSensor | Max/MSP | Multiple | Download |
