IOtech MultiScan 1200, Руководство пользователя

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176 Chapter 12: System Configuration TempScan / MultiScan User's Manual
To Compute the MultiScan/1200 Scan Interval
To compute the time interval for the MultiScan/1200 to acquire one scan, use the following formulas:
•
For a 60-Hz Line Cycle: Scan Interval equals:
Is-m = Cv x (Wv + 12) x R3
•
For a50-Hz Line Cycle: Scan Interval equals:
Is-m = Cv x (Wv + 12) x R4
Where:
Is-m
= Scan Interval for the MultiScan/1200, milliseconds.
Cv
= Channels, variable number of configured channels in the scan.
Wv
= Sampling Weight, variable number of samples per channel.
R3
= Sampling Rate, constant of 0.52083 milliseconds (per sample) for a 60-Hz line cycle.
R4
= Sampling Rate, constant of 0.62500 milliseconds (per sample) for a 50-Hz line cycle.
For example, if 148 channels are configured, the disposition of these channels will not be a factor.
Using the scan interval formula for a MultiScan/1200 system with a 60-Hz line cycle, if the system is
configured to take 1 sample per channel, gives:
Is-m = 148 x (1 + 12) x 0.52083 millisec.
Is-m = 148 x 13 x 0.52083 millisec = 1002 millisec = 1.002 seconds.
Meanwhile, the following table shows how the fast mode scan rate varies when the number of
configured channels increases where these MultiScan/1200 channels are all adjacent to each other, and
are using the default sampling weight of 32 samples per channel.
Variations of the MultiScan/1200 Fast Mode Scan Rate
Number of Number of Scan Rate (Hz)
12-Channel Selected 60-Hertz Line Cycle 50-Hertz Line Cycle
Blocks Channels Hertz seconds Hertz seconds
1 12 3.636 0.275 3.030 0.330
2 24 1.818 0.550 1.515 0.660
3 36 1.212 0.825 1.010 0.990
4 48 0.909 1.100 0.758 1.320
5 60 0.727 1.375 0.606 1.650
… … … … … …
10 120 0.3636 2.750 0.3030 3.300
… … … … … …
50 600 0.0727 13.750 0.0606 16.500
… … … … … …
60 720 0.0606 16.500 0.0505 19.800
61 732 0.0596 16.775 0.0497 20.130
62 744 0.0587 17.050 0.0489 20.460
Note: (1) The number of selected channels refer to configured channels which are all adjacent to
each other. (2) These values were obtained from the above MultiScan/1200 scan interval
equations.