ADLINK DAQe-2006 - Manual (Page 82)

70 Operation Theory
should be TTL-compatible and the minimum pulse width
is 20 ns.
5. DA_TRIG, the trigger signal for the D/A operation, which
could be derived from external digital trigger, analog trig-
ger, internal software trigger, and SSI_AD_TRIG. Refer
to section 4.5 for detailed description.
6. DAWR, the update signal to initiate a single D/A conver-
sion, which could be derived from internal counter,
AFI[1] or SSI_DAWR. Note that this signal is edge-sensi-
tive. When using AFI[1] as the external DAWR source,
each rising edge of AFI[1] would bring an effective
update signal. Also note that the AFI[1] signal should be
TTL-compatible and the minimum pulse width is 20 ns.
Auxiliary Function Inputs (AFI)
You can use the AFI in applications that take advantage of exter-
nal circuitry to directly control the DAQ-/DAQe-/PXI-2016/2010/
2006/2005 card. The AFI includes two categories of timing signals:
one group is the dedicated input, and the other is the multi-func-
tion input. Table 4-9 illustrates this categorization.
Category Timing signal Functionality Constraints
Dedi-
cated
input
EXTTIMEBASE
Replace the
internal TIME-
BASE
1. TTL-compatible
2. 1MHz to 40MHz
3. Affects on both A/D and D/A
operations
EXTDTRIG
External digital
trigger input for
A/D operation
1. TTL-compatible
2. Minimum pulse width = 20ns
3. Rising edge or falling edge
EXTWFTRG
External digital
trigger input for
D/A operation
1. TTL-compatible
2. Minimum pulse width = 20ns
3. Rising edge or falling edge
Table 4-9: Auxiliary Function Input Signals and Functionalities