Object-oriented API for DATAQ DI-2008
Project description
Purpose
To provide an easy-to-use, object-oriented instrument interface for the DATAQ DI-2008 from within any Python environment.
The intent of this project is not to provide an API that will be useful in 100% of use cases, but will target the 90%. In my experience, most of us need pretty basic functionality and have only modest timing requirements when working with such instrumentation. As a result of this, the API will attempt to abstract away the lowest-level functionality which may result in a hiding or loss of feature implementation available in the hardware. If this happens to you, feel free to use the nuts and bolts exposed herein to inform your own development or, better yet, send us a pull request!
Check out the documentation!
Installation
The hardware drivers must be installed before this package may be utilized. Hardware drivers may be downloaded from the manufacturer's product page.
Once drivers are installed:
$> pip install di2008
Project Status and Future
The objects provided are tested and demonstrated to function well, however, there are still some features that have not been implemented.
Items marked out have already been completed. The list is in approximate order of priority and marked out items have been completed.
Implement Analog Scan ListcompleteRead ThermocouplescompleteRead Analog InputscompleteRead Rate Inputcomplete- Read Event Input
- Read Counter Input
Read Digital Input(s)completeWrite to Digital Outputscomplete- Better sample hardware timing control
- Hardware Synchronization
Usage
Regarding the specifics of usage, it may be very helpful for the user to read the device documentation so that some of the concepts enshrined herein are more precisely interpreted. Specifically, the concept of a "scan list" is somewhat unique to the product and difficult to abstract. As the project matures, more of the hardware idiosyncrasies are expected to be exposed to the user.
Deployment
When deploying using pyinstaller
in a windows environment, the pyusb
library doesn't
play well with libusb-1.0.dll
, so you will need to package libusb0.dll
into your
pyinsteller *.spec
file using the following line:
datas=[('C:\\Windows\\System32\\libusb0.dll', '.'),],
Hardware Setup
Place device into 'USB' mode, not COM mode!!!
- Disconnect from USB
- Wait 5 seconds
- Connect to USB and press button on side rapidly until LED changes
The device setting is persistent and will not need to be changed again.
If you see a COM port in your device manager with the label DATAQ DI-2008
then the device is NOT in the correct mode!
Software Setup
To read a few analog inputs, device setup is relatively simple.
- Define the ports
- Create the
Di2008
instance - Add the scan list
- Start the scanning process
- Read inputs at whatever timing is desired as the inputs will be updated "live"
Some sample code might be more illuminating. A simple script to set up the scan list and to print the values every second:
from time import sleep
from di2008 import AnalogPort, RatePort, Di2008
# create each of the inputs that need to be sampled
an0 = AnalogPort(1, analog_range=10.0, filter='average')
an1 = AnalogPort(2, thermocouple_type='j')
an2 = AnalogPort(3, thermocouple_type='j')
rate = RatePort(5000)
daq = Di2008()
daq.create_scan_list(
[an0, an1, an2, rate]
)
daq.start()
while True:
print(f'{an0.value:.02f}')
print(f'{an1.value:.02f}')
print(f'{an2.value:.02f}')
print(f'{rate.value:.02f}')
print()
sleep(1.0)
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