Honeywell CIU 888 Configuration Manual page 99

NOTE: How to configure scan period for gauges in a Field Port.
Part No.: 4417584_Rev12
Getting Started
Properties
Temperature profile scan
period
* Refer to TABLE 3-1 for additional information.
For each temperature profile scan, CIU 888 reserves a time period of 3
minutes so that enough field port bandwidth is given for scanning periodic
foreground and background measurement items.
When the user enables temperature profile scan for a tank through "CIU 888
Service tool" or "Modbus host system" the CIU 888 Service tool runs the
following logic to determine whether the temperature profile scan enable can
be accepted or not without affecting the regular periodic scan items
(foreground and background).
Temperature profile scan enable is allowed if the available slots is greater than
or equal to 0.
Available slots = Total slots – ((Number of frames / 1) * Number of Gauges
in 1st frame) - ((Number of frames / 2) * Number of Gauges in 2nd frame) -
((Number of frames / N) * Number of Gauges in Nth frame)
where
Total slots = Number of frames * (Number of slots per frame - 1)
Number of frames = Maximum_scan_period / frame interval
Maximum_scan_period is the highest temperature profile configuration
period in that field port or field port group.
Frame interval = Number of slots per frame * 3
Number of slots per frame = Minimum_scan_period / 3
Minimum_scan_period = smallest temperature profile scan period in that
field port or field port group
Number of Gauges in N
Examples:
a) Field port has 3 gauges with 15 minutes as temperature profile scan period
and the user enables one more gauge for temperature profiles scan with
scan period as 15 minutes.
number of slots = 15/3 = 5
frame interval = 5 * 3 = 15
number of frames = 15/15 = 1
total slots = 1 * (5-1) = 4
number of gauges that comes once in one iteration i.e, gauges with configu-
ration period between 15 and 29 = 4
available slots = 4 - (1*4) = 0
The CIU 888 accepts the temperature profile scan enable for the 4th gauge.
Configuration Manual
CIU 888
Description
This parameter defines the time period within which the
temperature profile data needs to be collected from a
BPM gauge. The scan period is defined in terms of min-
utes.
th
frame = (configuration period / (Frame Interval * N))
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