Sentry Sample Sequencer 5 Installation, Operation And Maintenance Manual page 43

5.3.2 Batch Mode
This mode is for analyzers that take a "bite" or batch of sample and then spend some time
analyzing it before outputting a new fixed 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.
Figure 37 illustrates the timing diagram for the batch mode, showing how each sample stream
is switched when the analyzer outputs an end-of-batch signal to the Sample Sequencer. If the
Sample Sequencer does not receive an end-of-batch signal, the Sample Sequencer will never
advance to the next sample. Upon receiving an end-of-batch signal from the analyzer, the
Sample Sequencer reads the analyzer value, updates the Track and Hold output, and closes
the point identification relay. Note: The updated Track and Hold output and point
identification relay are for the previous sample point. The open valve number will never
match the closed relay point identification in the batch mode.
The following considerations should be made when determining the timing for your batch
mode system:
End-of-Batch:
completed and the analyzer is ready to begin a new analysis.
Analyzer Alarm: The Sample Sequencer receives this signal when the analyzer is in
alarm, such as a loss of sample flow condition. Once the analyzer alarm signal is
received the Sample Sequencer will start the Sample timer, and replicate the analyzer
alarm for use by external recorders and control systems.
Sample Time: The Sample time in the batch mode is 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 the Sample time times out, the Sample Sequencer will close the current sample
point and proceed with the next sample point. Since the Analyzer Alarm input may serve to
indicate more than a loss of sample flow, the Sample time should be set to give the
analyzer sufficient time to attempt to complete an analysis and output an End-of-Batch
indication.
SPD 5.5.15
See Appendix B for instructions about connecting a
Hach 5000 analyzer to the Sample Sequencer.
Timing Considerations for the Batch Mode
The Sample Sequencer receives this signal when the analysis is
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