1120 User Guide
Getting Started
Welcome to the 1120 user guide! In order to get started, make sure you have the following hardware on hand:
- 1120 - IR Distance Adapter
- Any Phidget with a Voltage Ratio Input port, here are some compatible products. We will be using the VINT Hub for this guide.
- USB cable and computer
- Phidget cable
- Flexiforce sensor
Next, you will need to connect the pieces:
- Connect the 1120 to the 1018 with the Phidget cable.
- Connect the Flexiforce sensor to the 1120. Polarity doesn't matter. See the technical section for details.
- Connect the 1018 to your computer with the USB cable.
Now that you have everything together, let's start using the 1120!
Using the 1120
Phidget Control Panel
In order to demonstrate the functionality of the 1120, we will connect it to the 1018, and then run an example using the Phidget Control Panel on a Windows machine.
The Phidget Control Panel is available for use on both macOS and Windows machines. If you would like to follow along, first take a look at the getting started guide for your operating system:
Linux users can follow the getting started with Linux guide and continue reading here for more information about the 1120.
First Look
After plugging in the 1120 into the 1018, and the 1018 into your computer, open the Phidget Control Panel. You will see something like this:
The Phidget Control Panel will list all connected Phidgets and associated objects, as well as the following information:
- Serial number: allows you to differentiate between similar Phidgets.
- Channel: allows you to differentiate between similar objects on a Phidget.
- Version number: corresponds to the firmware version your Phidget is running. If your Phidget is listed in red, your firmware is out of date. Update the firmware by double-clicking the entry.
The Phidget Control Panel can also be used to test your device. Double-clicking on an object will open an example.
Voltage Ratio Input
Double-click on a Voltage Ratio Input object in order to run the example:
General information about the selected object will be displayed at the top of the window. You can also experiment with the following functionality:
- Modify the change trigger and/or data interval value by dragging the sliders. For more information on these settings, see the data interval/change trigger page.
- Select the 1120 from the Sensor Type drop-down menu. The Sensor Value will now return a value between 0 and 1. To make sense of these values, view the technical details section below
Technical Details
Calibrate
The FlexiForce Force sensor is a piezoresistor that has a very large resistance when it is not loaded (in the range of MegaOhms). The resistance decreases as more force is applied. Tekscan offers sensors with standard force ranges, such as 0-1 lbs, 0-25 lbs, and 0-100 lbs. The same adapter board can be used for all three ranges. Because the expected part-to-part variance between FlexiForce sensors is as high as 40%, it is imperative that you calibrate your sensor and determine the specific formula which applies to your sensor. For information on how to calibrate your sensor, refer to the FlexiForce User Manual from Tekscan.
Interface FlexiForce Sensors
The FlexiForce sensors are easy to interface to the 1120. They can be plugged into the Interface cable that is included. The other end of the cable has been stripped and tinned so that they can be easily inserted into the terminal block. This is useful if a longer cable is needed, as wires can be soldered to the stripped ends. The polarity of the FlexiForce sensors does not matter. If a larger force range is desired, a resistor on the Adapter board can be replaced. This resistor is designated as RGAIN on the board and has a default value of 15kΩ. When the RGAIN resistor value is reduced, the sensor becomes less sensitive and more force can be applied before saturating the output. Conversely, if the RGAIN value is increased, the sensitivity increases and the output saturates at a lower applied force. If RGAIN is changed, calibration with known forces will have to be done to determine the proper formula. Based on limited testing, RGAIN=5kΩ will give enough range to measure up to 1000 lbs with the 100 lbs Flexiforce sensor. Changing the gain by much larger amounts can cause sensor instability and is not recommended. Also note that adjusting the gain is not a substitute for calibrating and conditioning the sensor. You should look at the manual for the sensor you are using and follow all calibration procedures contained therein before resorting to adjusting the gain value to achieve accurate results.
Measurement Accuracy
To obtain the most accurate results, it is recommended that the sensor rests on a smooth surface and the object is only on the sensing pad and centered as much as possible. This can be achieved by using a small disc (included) that is just large enough to cover the sensing pad, and then placing the full force on the disc. Without the disc, the object may rest on the surrounding surface and record the force inaccurately. Care must also be taken to avoid jagged or sharp edges on the sensing pad, as it can affect the measurement as well as potentially puncture the pad. The pad at the end of the strip is the only place where force is sensed. Any force along the rest of the strip is ignored. The longer the object rests on the sensing pad, the more the sensor voltage will drift and vary slowly in value. It is very difficult to compensate for the drift since different constant forces will produce different drift rates. For this reason, the average accuracy of this sensor is approximately 5%.
Phidget Cable
The Phidget Cable is 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.
What to do Next
- Programming Languages - Find your preferred programming language here and learn how to write your own code with Phidgets!
- Phidget Programming Basics - Once you have set up Phidgets to work with your programming environment, we recommend you read our page on to learn the fundamentals of programming with Phidgets.
