ACR Electronics SmartReader Plus Manuel d'utilisateur télécharger pdf (Page 68)

SmartReader Data Loggers

1.11.6 Counting Modes and Equations

There are two counting modes for the SmartReader 9, Normal Rate and Accumulate mode.

These modes are selected using TrendReader software. The mode you select applies to both

logger channels. Make sure you choose equations for both channels that match the counting

mode.

Normal Rate Mode

The Normal Rate mode counts and records a totalized reading in a buffer, then restarts

counting at a fixed rate of once every eight seconds. The logger uses these eight-second

totals to determine the actual reading it records in memory. Depending on how you set up

your logger's sampling rate, the readings you obtain may be calculated by averaging the

eight-second counts that make up the logger's sampling rate. For example, if your logger is

set to take a reading every two minutes, then each reading the logger stores will consist of the

average of fifteen eight-second intervals. If the logger counts 150 pulses in the first

eight-second interval, and there are no pulses during the other fourteen eight-second intervals,

your logger will average all fifteen intervals and store a raw byte value of 10. This indicates

that during the two-minute interval there were an average of ten pulses per eight-second time

period. The Normal Rate mode equations read out directly in Hz (pulses per second) both in

Realtime display and during graphing.

Accumulate Mode

The Accumulate mode counts and records a totalized reading to memory at a frequency

matching the sampling rate that you have set for your logger. For example, if your logger is

set to take a reading every two minutes, then each reading the logger stores will consist of the

total of all the pulses that occurred during the two minutes. The Accumulate mode equations

read out in pulses per logger time interval during graphing. In Realtime mode, TrendReader

software displays pulses per eight-second period.

Equations

There are six possible methods of operation for each of the SmartReader 9's two pulse

channels. That is because there are three rate select jumper settings and two counting

modes, Normal Rate mode and Accumulate mode. To collect correct data, you must select

the equation that relates to your logger settings. The Rate Select Table provides you with a

summary of these equations.

For each equation number listed in the following table, the corresponding information is

provided:

· The counting mode the logger has been set to operate in ("A" for Accumulate mode, "N"

for Normal Rate mode).

· The required setting for the rate select jumper on your logger. The maximum number of

pulses that this configuration can count up to during an eight-second period (for normal

rate mode) or the logger's sampling rate (for accumulate mode).

· The contents of the equation itself which you can use to create custom equations in

your own choice of engineering units (i.e. flow rate in gpm, traffic in cars/minute, or

speed in km/hour).

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ACR Electronics SmartReader Plus Manuel d'utilisateur Page 68