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Chapter 2 Function Reference — Line_Change_Attribute
NI-DAQ FRM for PC Compatibles 2-278
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National Instruments Corporation
attribID = ND_LINE_FILTER
(valid only for lineNum = ND_PFI_0 through ND_PFI_39)
attribID =
ND_LINE_FILTER
(valid only for lineNum = ND_RTSI_0 through ND_RTSI_6 and
ND_RTSI_CLOCK
)
Using This Function
When attribID = ND_LINE_FILTER and attribValue = ND_SYNCHRONIZATION_ONLY,
Line_Change_Attribute helps the 6602 device synchronize itself with external clock
pulses.
The RTSI lines can accept an external clock as one of their inputs. The external clock will
probably not be in synchronization with the internal clock on the 6602 device. If the two
clocks are not in synchronization, it is possible for the 6602 device to miss or miscount a
signal. Calling
Line_Change_Attribute with attribID = ND_LINE_FILTER and
attribValue =
ND_SYNCHRONIZATION_ONLY establishes synchronization by delaying the
external clock referenced pulse until the 6602 can count the pulse. The 6602 can count the
external clocked pulse during the next internal clock pulse. Refer to your 6602 device manual
for more details.
Example
status =
Line_Change_Attribute
(1,
ND_PFI_36
,
ND_LINE_FILTER
,
ND_SYNCHRONIZATION_ONLY
)
;
This example synchronizes any pulses coming in on internal line 3 with the internal clock of
the TIO chip.
attribValue Description
ND_SYNCHRONIZATION_ONLY
Synchronizes the signal using the internal clock
ND_100KHZ
Filters the signal using a 100 kHz filter
ND_500KHZ
Filters the signal using a a 500 kHz filter
ND_1MHZ
Filters the signal using a 1 MHz filter
ND_5MHZ
Filters the signal using a 5 MHz filter
ND_NONE (default)
Uses no filtering or synchronization. The signal in this
case passes through “as is.” This is the default setting.
attribValue sourceSpec
ND_SYNCHRONIZATION_ONLY
Synchronizes the internal line with the internal clock
ND_NONE (default) Uses no synchronization. The signal passes through
“as is.” This is the default setting.