Integral - Allen-Bradley Micro800 General Instructions Manual

Chapter 18
Process control instructions

INTEGRAL

532
INTEGRAL integrates a real value.
INTEGRAL operation
•
When the INTEGRAL function block is first initialized, its initial values
are not considered. Use the R1 parameter to set the initial values for a
calculation.
•
To prevent loss of the integrated value, the integration value is not cleared
automatically when the controller transitions from PROGRAM to RUN or
when the RUN parameter transitions from FALSE to TRUE. Use the R1
parameter to clear the integral value when first transitioning the controller
from PROGRAM to RUN mode and when starting a new integration.
•
We recommend you do not use the EN or ENO parameters with this
function block because the cycle time calculation will be disrupted when
EN is FALSE, resulting in an incorrect integration. If you choose to use the
EN or ENO parameters, toggle the R1 parameter with EN equal to TRUE
to clear the current result and ensure correct integration.
•
Integration is performed with a time base of milliseconds (that is,
integrating an input of 1 with an initial value of 0 for 1 second will result in
a value of 1000). To convert the output of the instruction to units of
seconds, divide the output by 1000.
•
If the CYCLE parameter value is less than the cycle timing of the execution
of the device, the sampling period is forced to the cycle timing.
•
XIN sampling and function block executions occur every cycle time + Scan
Time Jitter.
•
For a given user program, Scan Time Jitter varies from controller to
controller.
•
The cycle time determines the sensitivity of the Integral function block.
Changes occurring in XIN between two samplings (or within the cycle
time) are not taken into account when the integral XOUT value is
calculated.
Rockwell Automation Publication 2080-RM001D-EN-E - February 2015