Flush Return Data Buffer

NI-Motion VI

Flush Return Data Buffer

Clears the Return Data Buffer (RDB) by deleting all of the buffered data.

Details

Device Compatibility

DeviceCompatibility
7330
Y
7340
Y
7344
Y
7350
Y
7390
Y
NI SoftMotion Controller for CANopen—Accelnet
N
NI SoftMotion Controller for CANopen—Xenus
N
Board ID is a unique number assigned by Measurement & Automation Explorer (MAX) used to send and receive commands and data to or from a specific NI motion controller.
error in (no error) describes error conditions that occur before this VI runs. The default input of this cluster is no error. If an error already occurred, this VI returns the value of error in in error out. The VI runs normally only if no incoming error exists. Otherwise, the VI passes the error in value to error out. The error in cluster contains the following parameters:
status is TRUE if an error occurred before this VI was called, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.
Bd ID Out is provided for flow control. You can string together NI-Motion VIs by wiring the Bd ID Out terminal of one VI to the Board ID terminal of the next VI.
error out contains error information. If error in indicates an error, error out contains the same error information. Otherwise, it describes the error status that this VI produces.
status is TRUE if an error occurred, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.

Using This VI

The Flush Return Data Buffer VI clears the Return Data Buffer by repeatedly reading the RDB until the buffer is empty. All return data packets in the RDB are deleted and this VI returns nothing.

You typically use the Flush Return Data Buffer VI after an error condition when the data in the Return Data Buffer is no longer valid or relevant. This VI is also useful for flushing the RDB after a programming error has caused the buffer to become skewed. Buffer skew is when the data returned by a read VI using the default input vector of 0xFF does not return the expected data but rather returns data requested by a previous VI.

Refer to the motion controller documentation for more information about low-level communications protocols and return data packets.