Operator`s manual

Figure 4-4. The trigger input maybe set for polarity and be enabled or disabled.
4.2.2 Trigger Input
The trigger input line, TrigIn, maybe set for a positive or negative polarity using the SCANTriggerInState()
command. Under normal operation, the TrigIn line has no effect on the operation of the scanner. It maybe used to
synchronize other test equipment such as in the Triggered Auto Scan and Triggered Scan, where an external event
initiates scanning operation. The level of the TrigIn line maybe monitored using the SCANGetTriggerIn()
command.
4.2.3 Auto Scan Operation
This operation requires that the Scanner be in one of the following configurations: TwoWire, FourWire, SixWire,
TwoGroups, or FourGroups. The Auto Scan operation is a software initiated Scan sequence. Issuing
SCANAutoScan() command triggers an automatic scanning operation, in which the first channel from the first
location in the Scan List table is selected first, followed by a delay equal to t-Step. Channels are selected
sequentially from the Scan List. The total number of points in the scan is controlled by the iPoints parameter passed
by the SCANAutoScan() function, which must be a value between 1 and 192. This mode maybe terminated by
sending SCANAbort() command to the Scanner during the scan. Use the SCANOpenAllChannel() function at the
end of the scan, if you wish to open the last selected channel. The Trigger output signal can be used to synchronize
other instruments to the SMX4000 Scanner. The value of t-Step and t-Actuation can be set to generate a trigger
output signal for triggering instruments. For instance, setting the TrigOut polarity to positive sense (as in Figure 4-
6) will result in a positive edge to trigger an SMX2044 DMM, after a channel relay is closed and settled.
Figure 4-6. AutoScan is a software-initiated channel scanning procedure.
4.2.4 Triggered Auto Scan Operation
This operation requires that the Scanner be in one of the following configurations: TwoWire, FourWire, SixWire,
TwoGroups, and FourGroups. The Triggered Auto Scan operation is a hardware-triggered version of the above
Auto Scan operation. The trigger polarity can be selected. The SCANTrigAutoScan() function sets the Scanner
into the Triggered Auto Scan mode, in which the Scanner waits for a trigger edge to initiate an Auto Scan operation.
Once a trigger is received, the first channel from the first location in the Scan List table is selected, followed by a
delay equal to t-Step, then the selection of subsequent channels as specified in the Scan List table. The Scanner
proceeds to sequentially select a total of iPoints. The last parameter is passed to the scanner by the
SCANTrigAutoScan() function. This value must be between 1 and 192. This may be terminated by sending
SCANAbort() command to the Scanner. Use the SCANOpenAllChannel() function if you wish to open the last
selected channel at the end of the scan.
21 Signametrics