Introduction

The Python API for Linux allows users to access and control supported Measurement Computing hardware using the Python language over the Linux platform. Python 2.7 and 3.4+ are supported.

The Python package name is uldaq. The uldaq package is implemented in Python as an interface to the UL shared object library.

The UL for Linux API provides structures and enumerations to manage connected devices, obtain information about device capabilities, and configure hardware settings.

Note

For performance reasons, data is returned in the Python API as arrays instead of lists.

The uldaq package is available on GitHub.

Installation

Refer to the README file for information about how to download the UL for Linux package and install the API.

Creating a Python program

When creating a UL for Linux program in Python, import the uldaq package to use in your code: import uldaq

Refer to the example programs and the API documentation in the Python API Reference for more information.

Example programs

UL for Linux example programs are available to run with MCC hardware. Refer to the README file for information about how to download and extract the examples.

Connect a supported Measurement Computing DAQ device to your system before running an example. Complete these steps to run a UL for Linux example:

1. Open a terminal window in the UL for Linux examples folder directory.

2. Enter ./file_name.py. For example, enter ./a_in.py to run the analog input example.

Users can also choose to import the example code into an IDE, such as PyCharm or Eclipse, and run the examples from that environment.

The example download file includes the following example programs:

Method	Description
a_in	Reads an A/D input channel. Demonstrates a_in().
a_in_scan	Scans a range of A/D input channels, and stores the data in an array. Demonstrates a_in_scan() and scan_stop().
a_in_scan_with_events	Performs an A/D scan using events to determine the data in an array. Demonstrates when data is available or when the acquisition is complete. The example also demonstrates how to retrieve the data when it becomes available. Demonstrates enable_event(), scan_wait() and scan_stop().
a_in_scan_with_queue	Creates a queue that sets individual channel ranges for an A/D scan. Demonstrates a_in_load_queue(), a_in_scan(), and scan_stop().
a_in_scan_with_trigger	Scans a range of A/D channels when a trigger is received, and stores the data in an array. This example shows how to obtain and configure trigger options. Demonstrates a_in_scan() and scan_stop().
a_in_scan_iepe	Enables IEPE mode for a range of A/D channels, and scans the specified A/D channels. Demonstrates a_in_scan() and scan_stop().
a_out	Writes a specified value to a D/A output channel. Demonstrates a_out().
a_out_scan	Performs a D/A scan. Data can be viewed with an oscilloscope or meter. Demonstrates a_out_scan() and scan_stop().
c_in	Sets the initial value of a counter and counts events. Demonstrates c_in() and c_clear().
c_in_scan	Scans a range of counter channels. Demonstrates c_in_scan(), c_load() and scan_stop().
c_in_scan_with_encoder	Scans a range of encoder channels. Demonstrates c_in_scan(), c_config_scan(), and scan_stop().
daq_in_scan	Simultaneously acquires analog, digital, and counter data. Demonstrates daq_in_scan() and scan_stop().
daq_in_scan_with_trigger	Sets up a trigger function, and simultaneously acquires analog, digital, and counter data when the trigger is received. Demonstrates daq_in_scan() and scan_stop().
daq_out_scan	Simultaneously outputs analog and digital data. Demonstrates daq_out_scan() and scan_stop().
d_bit_in	Configures multiple digital bits for input, and reads the bit values. Demonstrates d_config_bit() and d_bit_in().
d_bit_out	Writes a specified value to multiple digital output bits. Demonstrates d_config_bit() and d_bit_out().
d_in	Configures a port for input and reads the port value. Demonstrates d_config_port() and d_in().
d_in_scan	Configures a port for input and continuously reads it. Demonstrates d_config_port(), d_in_scan(), and d_in_scan_stop().
d_out	Configures a port for output and writes a specified value. Demonstrates d_config_port() and d_out().
d_out_scan	Configures the port direction and outputs digital data. Demonstrates d_config_port(), d_out_scan(), and d_out_scan_stop().
remote_discovery	Discovers remote Ethernet DAQ devices. Demonstrates get_net_daq_device_descriptor().
t_in	Reads a temperature channel. Demonstrates t_in().
tmr_pulse_out	Generates an output pulse at a specified duty cycle and frequency. Demonstrates pulse_out_start() and pulse_out_stop().

Supported hardware

Refer to the Hardware Reference section for a list of all supported Measurement Computing devices with links to supported UL for Linux capabilities.

Support

Measurement Computing Corporation

508-946-5100

Technical Support: www.mccdaq.com/support

Knowledgebase: kb.mccdaq.com

www.mccdaq.com