hil_read_digital :: Quanser C Functions

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hil_read_digital

Reads from digital inputs immediately.

Description

The hil_read_digital function reads from the specified digital input channels immediately. The function does not return until the data has been read.

Warning 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 inputs must be configured as inputs using this function. Failure to configure the digital I/O may result in the hil_read_digital function failing to read those inputs.

Prototype

t_error 
hil_read_digital(t_card card, const t_uint32 digital_channels[], t_uint32 num_channels, t_boolean buffer[]);

Parameters

t_card card

A handle to the board, as returned by hil_open

const t_uint32 [] digital_channels

An array containing the channel numbers of the digital inputs to be read.

Select a board type from the list for board-specific details: .

t_uint32 num_channels

The number of channels specified in the digital_channels array.

t_boolean [] buffer

An array for receiving the binary values read from the digital inputs. The array must contain num_channels elements. Each element in the returned buffer array will correspond to the same element in the digital_channels array.

Return value

The return value is 0 if the digital inputs are read successfully. 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_READ_DIGITAL_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_TOO_MANY_DIGITAL_INPUT_CHANNELS

Too many digital input channels were specified.

QERR_INVALID_DIGITAL_INPUT_CHANNEL

One of the digital input 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.

Requirements

Include Files	Libraries
hil.h	hil.lib;quanser_runtime.lib;quanser_common.lib

Examples


/*
* Read the first four digital input channels.
*/

t_uint32 channels[] = { 0, 1, 2, 3 };
t_boolean values[4];
t_error result = hil_read_digital(board, channels, ARRAY_LENGTH(channels), values);

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