Sentry Sample Sequencer 6 - Page 27

Sentry Sample Sequencer 6 Controller 27
 NOTE
The Track and Hold value and Point Identi cation are active during the sample time . The valve for this sample point is open
during both the sample time and the  ush time .
In Batch mode, sample time serves as a timeout timer that operates only when the analyzer is in alarm . While in alarm, if an
end-of-batch signal is not received before sample time expires, the Sample Sequencer 6 closes the current sample point and
proceeds to the next sample point .
Since the analyzer alarm input may serve to indicate more than a loss of sample  ow, sample time should be set to give the
analyzer suffi cient time to attempt to complete an analysis and output an end-of-batch indication.
Figure 10. Continuous Mode Timing Diagram
Batch Mode
Batch mode is for analyzers that take a “bite” or batch of sample and then spend some time analyzing it before
outputting a new  xed analog signal. Typical types are reagent additive, chromatographs, etc. When these analyzers
have completed an analysis, there is just one output value until the analyzer’s next cycle is completed. An end-of-batch
contact closure signal must be provided at the conclusion of a batch by the batch type analyzers. The Hach Series 5000
analyzer operates in this manner.
Timing Considerations for Batch Mode
Figure 13 illustrates the timing diagram for Batch mode, showing how each sample stream is switched when the