Sensoray 2410 API - Manual (Page 34)

Sensoray 24xx Programming Guide
30
Model 2426 Multi-Function I/O Module
7.4 Encoder Functions
7.4.1 s2426_ReadEncoderCounts()
Function: Read the encoder counter.
Prototype: BOOL s2426_ReadEncoderCounts( SESSION sess, u32 *err, u32 *counts, u32 *timestamp );
Returns: True if the operation was successful, otherwise False is returned and err will contain the associated error code.
Notes: Upon exit, counts will contain a snapshot of the encoder counter.
Example: // Get current counts from counter.
u32 err = ERR_NONE;
u32 counts;
if ( !s2426_ReadEncoderCounts( sess, &err, &counts, NULL ) )
printf( "Error: %s\n", s24xx_ErrorText(err) );
Example: // Get counts and timestamp.
u32 err = ERR_NONE;
u32 counts;
u32 tstamp;
if ( !s2426_ReadEncoderCounts( sess, 12, 3, &counts, &tstamp ) )
printf( "Error: %s\n", s24xx_ErrorText(err) );
else
printf( "counts=%d at t=%d microseconds\n", counts, tstamp );
7.4.2 s2426_WriteEncoderMode()
Function: Program the encoder interface operating mode.
Prototype: BOOL s2426_WriteEncoderMode( SESSION sess, u32 *err, u32 clock, u32 preload );
Returns: True if the operation was successful, otherwise False is returned and err will contain the associated error code.
Argument Description
sess Session handle obtained from s24xx_SessionOpen() .
err Pointer to error code. See Section 4.3.1 for details.
counts Pointer to buffer that is to receive the counts.
timestamp Pointer to buffer that will receive the timestamp. The timestamp is a snapshot of the
I/O module’s system timer at the moment
counts is sampled. Set to NULL if the
timestamp is not needed. See section 5.6 for more information about timestamps.
Argument Description
sess Session handle obtained from s24xx_SessionOpen() .
err Pointer to error code. See Section 4.3.1 for details.
clock Counter clock mode. Specify one of these values:
NONQUADRATURE - single clock phase (e.g., tachometer)
QUADRATURE_X1 - quadrature clock (e.g., encoder), count at clock frequency
QUADRATURE_X2 - quadrature clock, count at two times the clock frequency
QUADRATURE_X4 - quadrature clock, count at four times the clock frequency
preload Specifies whether an active edge on the index input will cause the counter to be parallel
loaded from the preload register. Specify one of these values:
ENC_PRELOAD_DISABLE - index active edge does not cause counts change
ENC_PRELOAD_ENABLE - index active edge causes counts to change to preload value