User`s guide

130 Agilent VISA User’s Guide
4 Programming via GPIB and VXI
The above function sets the VXI trigger line to TTL trigger
line 0 (VI_TRIG_TTL0). The following are valid VXI trigger
lines. (Panel In is an Agilent extension of the VISA
specification.)
Once you set a VXI trigger line, you can set up an event
handler to be called when the trigger line fires. See “Using
Events and Handlers” on page 57 for more information on
setting up an event handler. Once the VI_EVENT_TRIG event
is enabled, the VI_ATTR_TRIG_ID becomes a read only
attribute and cannot be changed. You must set this attribute
prior to enabling event triggers.
The VI_ATTR_TRIG_ID attribute can also be used by
viAssertTrigger function to assert software or hardware
triggers. If VI_ATTR_TRIG_ID is VI_TRIG_SW, the device is
sent a Word Serial Trigger command. If the attribute is any
other value, a hardware trigger is sent on the line
corresponding to the value of that attribute.
Table 32 VXI Trigger Lines and Values
VXI Trigger
Line
VI_ATTR_TRIG_ID Value
TTL 0 VI_TRIG_TTL0
TTL 1 VI_TRIG_TTL1
TTL 2 VI_TRIG_TTL2
TTL 3 VI_TRIG_TTL3
TTL 4 VI_TRIG_TTL4
TTL 5 VI_TRIG_TTL5
TTL 6 VI_TRIG_TTL6
TTL 7 VI_TRIG_TTL7
ECL 0 VI_TRIG_ECL0
ECL 1 VI_TRIG_ECL1
Panel In VI_TRIG_PANEL_IN