CompuScope SDK Manua.. - Egmont Instruments

gage_set_ext_clock_variables
Syntax
C:
void GAGEAPI gage_set_ext_clock_variables (int16 op_mode, uInt16 external_clock_delay,
float external_clock_rate);
Visual BASIC:
Sub gage_set_ext_clock_variables (ByVal op_mode As Integer, ByVal external_clock_delay As Integer,
ByVal exterrnal_clock_rate As Single)
Remarks
gage_set_ext_clock_variables is used to set the required variables for use of an external clock. Signal.
Not all CompuScopes are equipped with an external clock input. On some CompuScope models, such as
the CS12100, it is an optional modification, which must be purchased with the CompuScope.
gage_set_ext_clock_variables should be called before the gage_capture_mode routine. If you are using
an external clock, you must use the GAGE_EXTERNAL_CLOCK constant as the rate and multiplier
values when calling the gage_capture_mode routine.
op_mode is a current CopmuScope operating mode, which should be set using the constants
GAGE_SINGLE_CHAN or GAGE_DUAL_CHAN (or GAGE_QUAD_CHAN for digital CompuScopes).
The external_clock_delay parameter sets the clock delay to synchronize the external clock to the
CompuScope board. Using a value of -1 will let the drivers calculate this value. Use another value to
override this option. The values calculated by the driver will be 0 if the sample rate is greater than 5 MHz
or the maximum of 1 and 10,000 / external_clock_rate otherwise. It is recommended that –1 be used for
the external_clock_delay.
external_clock_rate is frequency of the signal connected to the EXTERNAL CLOCK input of the
CompuScope. It is important that this value be set correctly, since the CompuScope hardware needs to
know this value so that the drivers can set internal CompuScope timing parameters.
The frequency at which sampled data will be stored in memory may differ from the external_clock_rate.
For instance for the CS1602, the sampling rate is one-eighth of the external_clock_rate. For the CS12100
with the regular external clock upgrade, the sampling rate is one-half of the external_clock_rate, when the
CS12100 is in dual channel mode.
Return Value: None
See also: gage_capture_mode
Examples: C:
gage_set_ext_clock_variables (GAGE_SINGLE_CHAN,-1, 10000000.0);
Visual BASIC:
Call gage_set_ext_clock_variables (GAGE_SINGLE_CHAN,-1, 10000000.0)
CompuScope API Reference Manual 48