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SR9/SRP9 FAQ

Frequently Asked Questions for SmartReader 9 and SmartReader Plus 9

What is the accuracy of SR9 and SRP9 loggers?

The accuracy of the SRP9 is ±1 pulse/sample period.

The accuracy of the SR9 is:

32 HZ Channel: ±1 pulse/8 seconds

64 HZ Channel: ±2 pulse/8 seconds

128 HZ Channel: ±4 pulse/8 seconds

How does the SR9 work?

The SR9 keeps track of the number of times a switch opens and closes by maintaining a voltage potential across the input terminals on a continual basis. Every time the voltage potential changes from high to low (i.e. switch opening) and back to high again, (i.e. switch closing) the logger registers a count of '1'. Note: For "switch status" logging, see SmartReader Plus 8.

What is the minimum pulse length and minimum interval between pulses on the SR9?

Four milliseconds.

What is meant by jumper selectable frequencies on the SR9?

The SR-009 has 3 jumper selectable frequencies.  This is selected by placing a jumper wire on the terminal strip.  This determines whether the logger counts every pulse, every second pulse, or every fourth pulse.  This affects the logger in both the Average and Accumulate mode.

What is the Average mode in the SR9?

The Average mode adds up the number of pulses recorded in each 8 second period, then at the end of the sample interval, stores the average of each 8 second period and stores to memory.  E.g. If the logger is set to a 16 second sample interval and the logger sees pulses at 10Hz for the first 8 seconds and none for the next 8 seconds, the value stored to memory would be 5Hz.

What is the Accumulate mode in the SR9?

The Accumulate mode is designed for lower frequencies.  The Accumulate mode is always preferred over averaging, since it will be as accurate or better than the average mode.  In Accumulate mode, the logger will record up to 255 pulses per sample interval.  E.g. If the logger is set to a 10 minute sample interval and the jumper set to 32Hz, the maximum number of pulses it could record is 255 per 10 minutes. Thus the maximum frequency is 0.425Hz.  In this mode, the maximum frequency decreases as the sample interval increases.

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