Yokogawa Button Operated MV2000 - Manual (Page 52)

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Feature Overview
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Index
• How Numeric Values Are Displayed and Recorded
The range of displayable values for computed data, ignoring the decimal point, is
–9999999 to 99999999. The decimal place is determined by the location of the
decimal point on the computation channel’s minimum span value. Regardless
of maximum and minimum span value settings, all computed values within the
aforementioned range of displayable values will be displayed. Non-numeric values are
displayed in these circumstances.
Display/Recorded Value Computed Data Status
+Over • +Display range-out: When the computed result exceeds 99999999
• +Computation range-out: When the value exceeds approximately
3.4×10 38 in the middle of computation.
• When a computation error* occurs (You can select +Over or –Over.)
-Over • –Display range-out: When the computed result is less than -9999999
• –Computation range-out: When the value goes below approximately
–3.4×10 38 in the middle of computation.
• When a computation error* occurs (You can select +Over or –Over.)
* Computation errors occur when the following computations are carried out.
• X/0, SQR(–X), or LOG(–X)
• When a channel number set to Skip or Off is used in an expression
• Rolling Average
The computation channel’s computed value is the rolling average of the computed
result of the expression specified for the channel. The number of samples and the
sampling interval can be specified for each computation channel. The rolling average
is applied over the time corresponding to: the number of data samples × the sampling
interval. The maximum sampling interval is 1 hour, and the maximum number of
samples is 1500.
• Starting Computation Operations
You can configure the MV to start computation operations when you press START/
STOP.
• TLOG Computation
TLOG computation determines the sum, maximum value, minimum value, average,
or the difference between the maximum and minimum values of a specific channel for
each interval determined by a timer.
Timer Assignment
Timers are assigned separately to each channel.
Units in Sum Operations
When using the sum operation (TLOG.SUM), set the unit (referred to as sum scale) of
the values to be summed.
You can select from Off, /s, /min, and /h. For details, see the next page.
Resetting the TLOG Computed Value
You can select whether or not to reset the TLOG computed value at every interval.
The figure below illustrates the reset operation for sum computation (TLOG.SUM).
Example: Result of the TLOG.SUM computation
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Reset Reset Reset
Reset: On
Timer timeout
Reset: Off
When reset is On, the sum is calculated over each interval. When reset is Off, the sum
of all values since the beginning of computation is calculated.
Power Failure Operation, Handling of Abnormal Data, and Handling of
Overflow Data
See “Special Data Handling Cases and Exceptions” in this section.
1.9 Computation and Report Functions (/M1 and /PM1 options)