Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 378)

App-9
IM 04L31A01-01E
Appendix
App
Numerical Display
The range of displayed values of computed data is from –999999999 to 9999999
excluding the decimal point. The decimal point position corresponds to the position of
the decimal point of the upper and lower limit span of the computation channel. On the
numerical display, values are displayed if the computed data is within the above range
regardless of the upper and lower limits of span.
However, special displays are used for cases given in the table below.
Computed Data Status Computation Status Display
When the computed result exceeds 99999999 Positive display overrange + *******
When the computed result is less than –9999999 Negative display overrange – *******
When the value in the middle of the computation Computation overflow + *******
exceeds approx. 3.4 × 10 38 or below approx. or
–3.4 × 10 38 . – *******
During a computation error Error + *******
Computation error occurs when perform the
following computation.
• X/0
• SQR(–X)
• LOG(–X)
• If a channel number set to skip is entered in the equation
When the stack of the equation (see section 11.2) Error + *******
is greater than or equal to 17
When the stack of the control equation is greater Error + *******
than or equal to 35
Rolling Average
The rolling average of the computed result of the equation specified for the computation
channel is determined, and the result is displayed as computed data for that channel.
The sampling interval and the number of samples can be specified for each channel.
The maximum sampling interval is 1 hour, and the maximum number of samples is 64.
The initial setting is [Off] (do not perform rolling average).
Alarm
Up to 4 alarms can be set to each computation channel. The alarm types are high limit
alarm (H), low limit alarm (L), delay high limit alarm (T), and delay low limit alarm (t). The
hysteresis is fixed to 0.
Acquisition of Computed Data to the Internal Memory
Display Data and Event Data
Similar to measurement channels, the computed data of computation channels can be
acquired to the internal memory as display data/event data.
Manual Sample Data
The instantaneous values of computation channels are acquired to the internal memory
through manual sample operation. However, this excludes the measurement channels
that are turned [Off].
TLOG Data
The instantaneous values of all channels (excluding measurement channels set to skip
and computation channels set to Off) can be saved at intervals specified by a timer.
Note
TLOG computed data and TLOG data are not the same. TLOG computed data refers to the
result of the TLOG computation. TLOG data refers to the instantaneous data of specified
channels acquired at specified intervals.
No. of Characters in Equations
Measurement computation: 40 characters or less
Control computation: 120 characters or less
Appendix 2 Supplementary Explanation of the Computation Function