IOtech MultiScan 1200, User Manual

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174 Chapter 12: System Configuration TempScan / MultiScan User's Manual
Fast-Mode Scan Rate (Minimum Scan Interval)
However, the scan interval can also be set to run at the minimum scan interval , yielding the fastest scan
rate that the current system configuration will allow. This is referred to as fast mode . Either the
normal or acquisition scan interval can be set to fast mode , by specifying the following scan interval –
00:00:00.0
– in the
I
command. For example, the command –
I00:00:10.0,00:00:00.0
– will
set the normal scan interval to once every 10 seconds and set the acquisition scan interval to fast
mode . These two types of scan intervals may be queried any time via the
I?
command.
If fast mode is specified, the TempScan/1100 or MultiScan/1200 unit will acquire scans at the fastest
rate that the current system configuration will allow. This requires some explanation since the rate at
which scans are acquired, while the unit is in
fast mode , may vary greatly depending upon the number
of channels configured as well as the disposition of those configured channels.
Note: The High/Low/Last Registers, the alarms, and the level event (if programmed) are all updated
at the maximum scan rate (or once every minimum scan interval), independent of any other
timebase configuration.
Disposition of Channel Configuration (TempScan/1100 Only)
An important aspect of the TempScan/1100 channel configuration is the number of channels configured
within a
channel block . The TempScan/1100 groups its channels into channel blocks, where each
channel block consists of four channels. For example, the first channel block in the TempScan/1100
system consists of channels 1 through 4; the second, channels 5 through 8; and so on.
The disposition of the channels refers to the density of the total channels configured within the system,
or in other words, the number of channels skipped and not skipped over. The greater the density of the
channel blocks, that is, the greater the number of configured channels for a given channel range, the
better the sampling rate will be.
The variable in determining the minimum scan interval is the number of non-empty 4-channel blocks .
Once you determine the number of non-empty 4-channel blocks, you can calculate the minimum scan
interval using the appropriate formula for your 50-Hz or 60-Hz line cycle system.
Example Disposition of TempScan/1100 Channel Configuration
4-Channel Block Channels In Use? 4-Channel Block Channels In Use?
1 1,2, 3, 4 Yes 16
61,62, 63,6 4 No
2 5 , 6, 7, 8 Yes 17
65, 66, 67, 68 No
3
9, 10, 11, 12 No
18
69, 70, 71, 72 No
4 13, 14, 15 , 16 Yes 19
73, 74, 75, 76 No
5
17, 18, 19, 20 No
20
77, 78, 79, 80 No
6
21,22, 23,24 No
21
81,82, 83, 84 No
7
25, 26, 27, 28 No
22
85, 86, 87,88 No
8
29, 30, 31, 32 No
23
89, 90, 91, 92 No
9
33, 34, 35, 36 No
24
93, 94, 95, 96 No
10
37, 38, 39, 40 No
25 97, 98, 99, 100 Yes
11
41,42, 43, 44 No
26 101 , 102, 103, 104 Yes
12
45, 46, 47, 48 No
27
105, 106, 107, 108 No
13
49, 50, 51,52 No
28
109, 110, 111, 112 No
14
53, 54, 55, 56 No
29
113, 114, 115, 116 No
15
57, 58, 59, 60 No
30
117, 118, 119, 120 No
Note: (1) Refer to the following example on scan interval computation where nine (9) channels 1, 2,
3, 4, 5, 7, 15, 100, and 101 are configured. (2) This table only shows 30 of the 248 maximum
4-channel blocks (992 channels) for the fully-expanded TempScan/1100 system.
Note: The disposition of the channel configuration does not affect MultiScan/1200 operation.