22
Model 7706 module
Limits and analog trigger
The limit subsystem and analog scan triggering works the same for the TOTalize function as for any other Model 2700 function
with the exception that only the UPPer limit is evaluated. The LOWer limit setting is ignored by the TOTalize function. The
TOTalizer MUST be monitoring in order to initiate a scan based on a Totalizer limit. When a scan is initiated by a TOTalizer
count, and the Totalizer type is set to ‘READ’, the limit that initiated the scan is removed from the ROUTe:SCAN:TSOurce list
so that the Model 2700 only runs through the scan list once. Otherwise, it would keep scanning since the TOTalizer count would
remain above the upper limit until reset.
Totalizer channel monitor scan example
For this example, Channel 25 of the Model 7706 is used to monitor the Totalizer with the Model 7706 inserted into slot 1 of the
Model 2700. This is an example of a four channel scan with Channels 101–103 measuring DC voltage while, as previously men-
tioned, Channel 125 monitors the Totalizer. As programmed, when the Totalizer reaches 100,000 counts, the scan is initiated.
Operation
A simplified model of scan operation is contained in
Figure 22
. The procedure for front panel operation and equivalent program-
ming commands for this simplified model is contained in
Table 1
. For this example, there are two modes of operation: monitor
and scan (see
Figure 22
). While in monitor mode, continuous Totalizer measurements are performed. The instrument remains
in the monitor mode until it reaches the high limit (in this example, the high limit is set to 100,000 counts). When this limit is
reached, the instrument changes over to scan mode (see
Figure 22
). The instrument is configured to scan four channels: three
DCV readings and the Totalizer channel (the buffer stores all four readings). After the fourth channel is measured, operation
turns again to the monitor mode to again measure Totalizer.
NOTE
When scan is initiated by a TOTalizer count with the type set to READ, the limit that initiated the scan is
removed from the ROUTe:SCAN:TSOurce list. This makes the unit run the scan list once. Otherwise, scan-
ning would continue until reset as long as the TOTalizer count remains above the upper limit. If the type is set
to RRES when a scan is initiated and after the Totalizer channel is scanned, it is reset to zero (0). If the Total-
izer again counts past the high limit set, the unit will run the scan list again, reset the count to zero, and so on.
