quanser.hardware.task.read_analog_write_analog

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Reads and writes the specified number of analog samples to the task's internal buffer.

Syntax

[input_voltages, samples_read, err] = task.read_analog_write_analog(num_samples, output_voltages)

Description

Reads and writes the specified number of analog samples to the task's internal buffer. This function will block until the requested number of samples have been read or can be written or the task is stopped. Note that the written samples are only transferred to the internal buffer. The samples may not appear at the outputs until later. Use task.flush to wait for all samples to be written to the outputs.

If no err output is provided then it throws an exception if an error occurs. In generated code it prints the error message. Use hil_get_error_message to get the message associated with an error code.

Parameters

task

Task instance returned by quanser.hardware.hil.task_create_analog_reader_analog_writer.

num_samples

The number of samples to read and write. This number must be less than or equal to the internal buffer size assigned to the task in the quanser.hardware.hil.task_create_analog_reader_analog_writer call.

output_voltages

A matrix of analog voltages to write. There must be one row for each channel and one column for each sample.

Outputs

input_voltages

A matrix of analog voltages read, as doubles. There is one row for each channel and one column for each sample.

samples_read

The number of samples written. This number will be equal to the number of samples specified unless the total number of samples specified in task.start has expired or the task has been stopped.

err

A negative error code or zero on success.

Examples

% Creates a task to read analog channel 5, and write to analog channels 0 and 3, with an internal buffer of 1000 samples.
task = board.task_create_analog_reader_analog_writer(1000, [0 3], 5);

% Uniformly distributed random voltages between -5V and +5V.
volts = 5*(rand(1,500)-0.5)*2;

% Writes 500 samples to analog channel 5. Won't block.
task.write_analog(volts);

% Start the task using SYSTEM_CLOCK_1 at 1 kHz. Collect up to 5000 samples.
task.start(-1, 1000, 5000);

for i=1:10
    % Uniformly distributed random voltages between -5V and +5V.
    volts = 5*(rand(1,500)-0.5)*2;

    % Reads 500 samples from analog channels 0 and 3 and writes 500 samples to analog channel 5.
    [v, n] = task.read_analog_write_analog(500, volts);
    ...
end;

% Make sure any samples remaining in the internal buffer have been written to the outputs.
task.flush;
task.stop;
task.close;