Hi, I am a complete novice with LabJack and do not know a huge amount about Raspberry Pi compared to what there is to know. I have got both a Raspberry Pi 3 and a LabJack T7 and am now looking to get them talking to each other so that I can control machinery in a lab via LabJack using Raspberry Pi. I was wondering if you could possibly help me on my way to getting the two components talking to each other. I have done the set up for the RaspPi and started getting to grips with Python IDLE3 but this is about where my experience stops, any help would be appreciated! Thank you!
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First, install the LJM library which is our Modbus interface for the T7 that provides USB/Ethernet/WiFi communications:
https://labjack.com/support/software/installers/ljm
The Linux armhf download is compatible with Raspberry Pi 3.
Second, download our LJM Python interface and examples:
https://labjack.com/support/software/examples/ljm/python
The Python download provides a helpful readme file, and the examples will provide a starting point with LabJack related Python code and testing.
Third, there is the T7 datasheet which documents hardware and Modbus names/addresses:
https://labjack.com/support/datasheets/t7
If you need further help with your machinery and the T7, we will need more details such as what is your machinery and its connections, what you want to control and what readings you need.
Thank you so much for your help, I have downloaded both the LJM library and the LJM python interface. I have been trying to run the example scripts however it keeps returning the error: 'No module named 'labjack'. Does this mean i have not successfully installed what you have suggest? Apologies for the naivety, i really am a novice with these two pieces of equipment.
Unfortunately at the moment i am unsure of the connections on the machinery, but i will be controlling a Sensirion humidity sensor and a molecular flow controller. I am afraid this is all the information i have on the equipment i will be trying to control
'No module named 'labjack' indicates the modules are not installed. There are instructions in the LJM Python download in its README and on this page on installing the modules:
https://labjack.com/support/software/examples/ljm/python
Basically download and unzip the contents, in a terminal go to the Python_LJM directory and run the installation command:
sudo python setup.py install
Afterwards try running the examples.
If you need more help with the hardware, let us know which Sensirion sensor you want to read, and what sort of control signal your flow controller is looking for.
Thank you, I thought i had installed it but obviously i hadn't done it properly and now the examples are running fine! Is there somewhere that explains what all of the examples are and what each of them do?
Thank you, i have got an EK-H5 humidity sensor from Sensirion and even this is proving tricky to get up and running. I am unsure about the Molecular Flow Controller as to what sort of control signal its looking for at the moment as they are yet to be delivered.
Hardware:
I don't see an EK-H5 in the list of Sensirion's humidity sensors. Can you clarify for us:
https://www.sensirion.com/en/environmental-sensors/humidity-sensor/
In regards to the examples, there is no text with a list of the examples and what they do. However in the download's examples if you look at the source files (.py) in a text editor/IDE, they do have comments describing what they do. The file name also hints at what it does, or what function it is demonstrating.
In Python, you can display the doc. of the Python LJM modules and its functions with help:
from labjack import ljm
help(ljm.ljm) # Display LJM module doc. (all functions)
help(ljm.ljm.eReadName) # Display eReadName (LJM_eReadName) function doc.