Measurement Computing TempScan/1100 User Manual
Page 69
TempScan / MultiScan User's Manual
879596
System Configuration 4-11
To Compute the TempScan/1100 Scan Interval
To compute the time interval for the TempScan/1100 to acquire one scan, use the following formulas:
• For a 60 Hz line cycle: Scan Interval is:
Is-t = [Next highest integer (Dv / 4)] x R1
• For a 50 Hz line cycle: Scan Interval is:
Is-t = [Next highest integer (Dv / 4)] x R2
Where:
Is-t
= Scan Interval for the TempScan/1100, milliseconds.
Dv
= Disposition, variable number of non-empty 4-channel blocks.
R1
= Sampling Rate, constant of 16.67 milliseconds (per 16-channel block) for a 60-Hz line cycle.
R2
= Sampling Rate, constant of 20.00 milliseconds (per 16-channel block) for a 50-Hz line cycle.
For example, if the nine (9) channels 1, 2, 3, 4, 5, 7, 15, 100, and 101 are configured, then there are five (5)
non-empty 4-channel blocks (refer to the table on disposition). Using the scan interval formula for a
TempScan/1100 system with a 60-Hz line cycle, gives:
Is-t = Next highest integer (5 / 4) x 16.67 millisec.
Is-t = 2 x 16.67 millisec = 33.33 millisec.
However, if nine (9) channels are configured less densely by every fourth channel from channel 4 through
36, then there are nine (9) non-empty 4-channel blocks. Using the same formula gives:
Is-t = Next highest integer (9 / 4) x 16.67 millisec.
Is-t = 3 x 16.67 millisec = 50.00 millisec.
Clearly, despite the identical number of configured channels, the disposition affects the TempScan/1100
scan interval. Meanwhile, the following table shows how the fast mode scan rate varies when the number
of configured channels increases where these TempScan/1100 channels are all adjacent to each other.
Variations of the TempScan/1100 Fast Mode Scan Rate
Number of
Number of
Scan Rate (Hz)
16-Channel
Selected
60-Hertz Line Cycle
50-Hertz Line Cycle
Blocks
Channels
Hertz
milliseconds
Hertz
milliseconds
1
16
60 16.67 50 20
2
32
30 33.33 25 40
3
48
20 50.00
16.67 60
4
64
15 66.67
12.50 80
5
80
12 83.33
10.00 100
…
…
… … … …
10
160
6.00 166.67 5.00 200
…
…
… … … …
50
800
1.20 833.33 1.00 1000
…
…
… … … …
60
960
0.909 1100.00 0.833 1200
61
976
0.984 1016.67 0.820 1220
62
992
0.968 1033.33 0.806 1240
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 TempScan/1100 scan interval
equations.