3. External Connection
28
VNA-300M-PCI
Connecting the External Trigger Input Signal
This section provides an example of using a BNC cable to connect the external trigger signal
(measurement start trigger).
Use a BNC cable (BNC-Bxxx; sold separately) or a similar item to connect an external device to the
BNC connector of the TRG.
The external trigger signal is a positive-logic, 3.3V, LVTTL level signal.
The TRG terminal can also be used for general I/O, but in this case, this terminal cannot be used to
receive external triggers.
Use the software to switch between external trigger input and general I/O.
Trigger
Input
BOARD
TRG
Target
3.3V
10k
Ground
50
SN74LVC245A
Shield cable
Figure 3.6. Connecting the External Trigger Input
CAUTION
-
You can use a 5V TTL or 5V CMOS signal for the input.
-
When the power turns on, the TRG terminal is set as an input.
Reference
For the operation timing of trigger I/O signals, refer to "Timing for Control Signal" in "Chapter 6
About Hardware".