Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 87

Processing details
■Analog integration processing
When the integration start signal (START) is TRUE, this function block performs integration processing to the value input from
the input variable IN and outputs the result from the output variable OUT_.
Integration start signal (START)
FALSE (Stop)
TRUE (Start)
T: Execution cycle
ILC: Input low-cut value
A_: Initial value
T: When RANGE is 1, T is 1 (s). When RANGE is 2, T is 60 (s). When RANGE is 3, T is 3600 (s).
Ex.
3
When a value of 0 to 5m /min is input, set RANGE to 2 because the input range is "/min".
The multiplying factor is  1m
■Integration start signal
When the integration start signal (START) is FALSE: The integration processing stops.
When the integration start signal (START) is TRUE: The integration processing starts.
Operation error
Error code Description
(SD0)
3400H An invalid operation (such as division by zero) is performed.
3402H Input data (START, IN), output data (OUT_), or operation constant (ILC, A_) is a subnormal number or NaN (not a number).
3403H An overflow has occurred.
3405H Input range (RANGE) is less than 1 or greater than 3.
Use M+P_SUM2_ to reduce the influence of information loss in the single-precision floating-point operation.
When M+P_SUM is used, information loss error in the single-precision floating-point operation may occur in
the integration operation (current value + up to the last integrated value).
Use M+P_SUM to maintain the compatibility with existing programs.
"Information loss" is an error caused by round-down or round-up of a small value when the extremely small
value is added to an extremely large value. This error occurs in a calculation system for the floating-point
operation. The real numbers of the programmable controllers are expressed in single-precision floating point
numbers.
The number of significant digits of real numbers in decimal is 6 or 7. An error occurs in the operation result of
the following real number operation.
0.013333 + 32768.0 = 32768.013333  32768.012
(current value + up to the last integrated value)
The logical operation result 32768.013333 is rounded down to 32768.012 and the increment 0.013333
decreases to 0.012. As the number of digits of the integral part of the integrated value increases, the number
of significant digits of the decimal part decreases.
Input (IN)
Optional
IN  ILC
IN > ILC
3
.
Output (OUT_)
OUT_ = Initial value (A_)
OUT_ = Last value
ΔT
OUT_=(IN× )+ previous value
T
5 CORRECTION OPERATION
5.7 Summation (M+P_SUM)
5
85