Table of Contents
hil_write_buffer
Writes the specified number of samples to the analog, PWM, digital and/or other channels at the indicated sampling rate.
Description
The hil_write_buffer function writes the specified number of samples to the output channels at the given sampling rate. The function does not return until the data has been written.
Many cards allow the digital I/O lines to be programmed as inputs or outputs. The digital I/O lines are configured as inputs or outputs using the hil_set_digital_directions function. All the channels which will be used as digital outputs must be configured as outputs using this function. Failure to configure the digital I/O may result in the hil_write_buffer function failing to write those outputs.
The interpretation of the PWM samples to be written depends upon the PWM mode. Typically the data is interpreted as a duty cycle, in which a magnitude of 0.0 denotes a 0% duty cycle and magnitude of 1.0 indicates a 100% duty cycle. The sign determines the polarity of the output for those boards supporting bidirectional PWM outputs. However, other PWM modes are possible with some boards. Refer to the hil_set_pwm_mode function for details.
Prototype
t_error hil_write_buffer(t_card card, t_clock clock, t_double frequency, t_uint32 num_samples, const t_uint32 analog_channels[], t_uint32 num_analog_channels, const t_uint32 pwm_channels[], t_uint32 num_pwm_channels, const t_uint32 digital_channels[], t_uint32 num_digital_channels, const t_uint32 other_channels[], t_uint32 num_other_channels, const t_double analog_buffer[], const t_double pwm_buffer[], const t_boolean digital_buffer[], const t_double other_buffer[]);
Parameters
t_card card
A handle to the board, as returned by hil_open .
t_clock clock
The clock used to time the operation. Note that some clocks allow faster sampling rates than others. See Clocks for more information on clocks.
Select a board type from the list for board-specific details: .
t_double frequency
The frequency in Hertz at which to write to the output channels. For example, if frequency is set to 1000, then the hil_write_buffer function will write all the selected channels every millisecond.
t_uint32 num_samples
The number of samples to collect. Each "sample" consists of all the output channels specified. For example, if frequency is set to 1000 and num_samples is set to 5000, then the hil_write_buffer function will return after 5 seconds with 5000 samples. If 3 channels in total have been selected, then the output buffer will contain 15,000 elements.
const t_uint32 [] analog_channels
An array containing the channel numbers of the analog outputs to which to write.
Select a board type from the list for board-specific details: .
If no analog channels are required then this parameter may be NULL
. In this case,
num_analog_channels must be zero.
t_uint32 num_analog_channels
The number of channels specified in the analog_channels array. This parameter may be zero.
const t_uint32 [] pwm_channels
An array containing the channel numbers of the PWM outputs to which to write.
Select a board type from the list for board-specific details: .
If no PWM channels are required then this parameter may be NULL
. In this case,
num_pwm_channels must be zero.
t_uint32 num_pwm_channels
The number of channels specified in the pwm_channels array. This parameter may be zero.
const t_uint32 [] digital_channels
An array containing the channel numbers of the digital outputs to which to write.
Select a board type from the list for board-specific details: .
If no digital channels are required then this parameter may be NULL
. In this case,
num_digital_channels must be zero.
t_uint32 num_digital_channels
The number of channels specified in the digital_channels array. This parameter may be zero.
const t_uint32 [] other_channels
An array containing the channel numbers of the other outputs to which to write.
Select a board type from the list for board-specific details: .
If no other channels are required then this parameter may be NULL
. In this case,
num_other_channels must be zero.
t_uint32 num_other_channels
The number of channels specified in the other_channels array. This parameter may be zero.
const t_double [] analog_buffer
An array containing the voltage values to write to the analog outputs. The array must contain num_analog_channels * num_samples elements. The array must be organized as a linear array of samples, with each sample consisting of a group of channels. For example, if analog output channels 0, 1 and 3 are being written, than the data must appear in the array as follows, where the numbers correspond to channel numbers:
0 |
1 |
3 |
0 |
1 |
3 |
... |
This ordering is equivalent to defining the buffer as:
t_double buffer[num_samples][num_channels];
If the buffer is defined in this way then pass the buffer as the
analog_buffer
argument using the syntax: &buffer[0][0]
.
If no analog channels were specified then this parameter may be NULL
.
const t_double [] pwm_buffer
An array containing the values to write to the PWM outputs. How these values are interpreted depends on the PWM mode. The PWM mode is configured using the hil_set_pwm_mode function. The array must contain num_pwm_channels * num_samples elements. The array must be organized as a linear array of samples, with each sample consisting of a group of channels. Refer to the analog_buffer parameter for an example.
If no PWM channels were specified then this parameter may be NULL
.
const t_boolean [] digital_buffer
An array containing the binary values to write to the digital outputs. The array must contain num_digital_channels * num_samples elements. The array must be organized as a linear array of samples, with each sample consisting of a group of channels. Refer to the analog_buffer parameter for an example.
If no digital channels were specified then this parameter may be NULL
.
const t_double [] other_buffer
An array containing the values to write to the other outputs. The array must contain num_other_channels * num_samples elements. The array must be organized as a linear array of samples, with each sample consisting of a group of channels. Refer to the analog_buffer parameter for an example.
If no other channels were specified then this parameter may be NULL
.
Return value
The return value is the number of samples successfully written. Otherwise a
negative error code is returned. Error codes are
defined in quanser_errors.h
. A suitable error message
may be retrieved using
msg_get_error_message
.
Error codes
QERR_HIL_WRITE_BUFFER_NOT_SUPPORTED
This function is not supported by the board-specific HIL driver for this board type.
QERR_INVALID_CARD_HANDLE
An invalid card handle was passed as an argument. Once a card has been closed using hil_close the card handle is invalid.
QERR_MISSING_ANALOG_OUTPUTS
The analog_channels argument is NULL. If the number of channels is greater than zero then a channel vector must be provided.
QERR_MISSING_ANALOG_OUTPUT_BUFFER
The analog_buffer argument is NULL. If the number of channels is greater than zero then a buffer must be provided.
QERR_TOO_MANY_ANALOG_OUTPUT_CHANNELS
Too many analog output channels were specified.
QERR_INVALID_ANALOG_OUTPUT_CHANNEL
One of the analog output channels that was specified is not a valid channel number. Channel numbers range from 0 to one less than the number of channels.
QERR_MISSING_PWM_OUTPUTS
The pwm_channels argument is NULL. If the number of channels is greater than zero then a channel vector must be provided.
QERR_MISSING_PWM_OUTPUT_BUFFER
The pwm_buffer argument is NULL. If the number of channels is greater than zero then a buffer must be provided.
QERR_TOO_MANY_PWM_OUTPUT_CHANNELS
Too many PWM output channels were specified.
QERR_INVALID_PWM_OUTPUT_CHANNEL
One of the PWM output channels that was specified is not a valid channel number. Channel numbers range from 0 to one less than the number of channels.
QERR_HARDWARE_CLOCK_IN_USE
One of the PWM output channels is based on a hardware clock that is already in use for another operation and the board-specific HIL driver for this board does not permit sharing of the hardware clock.
QERR_WRONG_CLOCK_MODE
One of the PWM output channels is based on a hardware clock that is in the wrong mode for this operation. Use the hil_set_clock_mode function to change modes.
QERR_MISSING_DIGITAL_OUTPUTS
The digital_channels argument is NULL. If the number of channels is greater than zero then a channel vector must be provided.
QERR_MISSING_DIGITAL_OUTPUT_BUFFER
The digital_buffer argument is NULL. If the number of channels is greater than zero then a buffer must be provided.
QERR_TOO_MANY_DIGITAL_OUTPUT_CHANNELS
Too many digital output channels were specified.
QERR_INVALID_DIGITAL_OUTPUT_CHANNEL
One of the digital output channels that was specified is not a valid channel number. Channel numbers range from 0 to one less than the number of channels.
QERR_MISSING_OTHER_OUTPUTS
The other_channels argument is NULL. If the number of channels is greater than zero then a channel vector must be provided.
QERR_MISSING_OTHER_OUTPUT_BUFFER
The other_buffer argument is NULL. If the number of channels is greater than zero then a buffer must be provided.
QERR_TOO_MANY_OTHER_OUTPUT_CHANNELS
Too many other output channels were specified.
QERR_INVALID_OTHER_OUTPUT_CHANNEL
One of the other output channels that was specified is not a valid channel number. Channel numbers range from 0 to one less than the number of channels.
QERR_DRIVER_INCOMPATIBLE_WITH_BOARD_DLL
The board-specific HIL driver passed an invalid parameter to the operating system specific kernel-level driver for the board. The board-specific HIL driver is likely not compatible with the operating system specific kernel-level driver for the board. Make sure both are up-to-date and compatible versions.
QERR_INTERNAL_BUFFER_TOO_SMALL
The board-specific HIL driver used an internal buffer that was too small for the operating system specific kernel-level driver for the board. The board-specific HIL driver is likely not compatible with the operating system specific kernel-level driver for the board. Make sure both are up-to-date and compatible versions.
QERR_OUT_OF_REQUIRED_SYSTEM_RESOURCES
There are not enough system resources to perform the requested operation. Try rebooting, requesting fewer samples, or adding more memory to your machine.
QERR_OUT_OF_MEMORY
There is not enough memory to perform the operation.
Requirements
Include Files |
Libraries |
---|---|
hil.h |
hil.lib;quanser_runtime.lib;quanser_common.lib |
Examples
/* * Write 5000 samples at 1 kHz to two analog output channels, two PWM output channels * and four digital output channels, using SYSTEM_CLOCK_1. */ t_double frequency = 1000; t_uint32 samples = 5000; t_uint32 analog_channels[] = { 0, 1 }; t_uint32 pwm_channels[] = { 0, 1 }; t_uint32 digital_channels[] = { 0, 1, 2, 3 }; t_error result; int i, j; static t_double analog_buffer[5000][2]; static t_double pwm_buffer[5000][2]; static t_boolean digital_buffer[5000][4]; for (i=0; i < samples; i++) { double time = i / frequency; for (j=0; j < ARRAY_LENGTH(analog_channels); j++) analog_buffer[i][j] = (j + 7.0) * sin(2*M_PI*time); for (j=0; j < ARRAY_LENGTH(pwm_channels); j++) pwm_buffer[i][j] = sin(2*M_PI*time); for (j=0; j < ARRAY_LENGTH(digital_channels); j++) digital_buffer[i][j] = (i % (j + 2)) >= (j + 2)/2; } result = hil_write_buffer(board, SYSTEM_CLOCK_1, frequency, samples , analog_channels, ARRAY_LENGTH(analog_channels) , pwm_channels, ARRAY_LENGTH(pwm_channels) , digital_channels, ARRAY_LENGTH(digital_channels) , NULL, 0 /* no other channels */ , analog_buffer , pwm_buffer , digital_buffer , NULL /* no other channels */ );
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