HIL Read Encoder Example

This example reads one sample immediately from four encoder input channels.

System Requirements

This example requires hardware supported by the HIL command set, such as the Q4 or Q8 hardware-in-the-loop card. Furthermore, the card must support immediate reads from an encoder channel.

Configuring the example

To set up the example for your data acquisition card, edit the M-file and change the board_type to the type of board being used. If you have more than one of these data acquisition cards in your machine, then also change the board_identifier variable to refer to desire board. Board identifiers are typically equal to the board number, with the first board being board '0', the next board being board '1', etc.

Running the example

Simply type the name of the example, hil_read_encoder_example, at the Matlab command prompt to run the example. It will read encoder input channels 0-3 and print the results to the Matlab command window. Typical output looks like:

ENC[0] = -471
ENC[1] = 0
ENC[2] = 0
ENC[3] = 0

Building code from the example

To build real-time code from the example for the QUARC Win64 target, execute the following command in the MATLAB Command Window:

qc_build_script('hil_read_encoder_example', 'win64');

The command may also be entered in this form:

qc_build_script('hil_read_encoder_example.rt-win64');

The qc_build_script command generates a build script called 'hil_read_encoder_example_build.m' and a main C file called 'hil_read_encoder_example_main.c'. It then invokes the build script to generate C code for the MATLAB script and to compile and link it into a QUARC executable called 'hil_read_encoder_example.rt-win64'. Running qc_build_script again will not overwrite the generated files, so they may be modified and the changes will be incorporated when qc_build_script is run again.

Running the generated executable

Before running the generated executable, open a QUARC Console so that the output of the executable may be seen. The QUARC Console need only be opened once. Use the command:

qc_script_console('hil_read_encoder_example.rt-win64', 'all');

The QUARC Console shows the standard output from any QUARC executable that is run on the target (since the 'all' option was specified).

To run the generated executable, type the following command in the MATLAB Command Window:

qc_run_script('hil_read_encoder_example.rt-win64');

The output from the executable will be seen in the QUARC Console:

QUARC Console output

Building code for a different target

Before building the code for a new target, change the board type and number of encoder channels to suit the board connected to the new target. In this case, a QUARC Linux Pi 3 target is used, so a Q2-USB (q2_usb) may be used. For a Q2-USB, the channels vector would have to be changed to 0:1 since it only supports two encoder input channels.

To build real-time code from the example for the QUARC Linux Pi 3 target, execute the following command in the MATLAB Command Window:

qc_build_script('hil_read_encoder_example', 'linux_pi_3', 'update');

The command may also be entered in this form:

qc_build_script('hil_read_encoder_example.rt-linux_pi_3', 'update');

The 'update' option causes the qc_build_script command to update the target type in the build script without rewriting the rest of the script. Hence, even if the script has been modified, the changes will be preserved. Only the target type will be changed. The command will then generate the C code for the MATLAB script and compile and link it for the new target type to produce the executable 'hil_read_encoder_example.rt-linux_pi_3'.

Running the generated executable on the new target

Before running the generated executable, open a QUARC Console so that the output of the executable may be seen. The QUARC Console for this new target need only be opened once. Use the command:

qc_script_console('hil_read_encoder_example.rt-linux_pi_3', 'all');

The QUARC Console shows the standard output from any QUARC executable that is run on the target (since the 'all' option was specified). Note that even though the QUARC Console is running on the host PC, it will be showing the standard output from QUARC executables run on the QUARC Linux Pi 3 target!

To run the generated executable, type the following command in the MATLAB Command Window:

qc_run_script('hil_read_encoder_example.rt-linux_pi_3');

The output from the executable will be seen in the QUARC Console.