Rockwell Automation DeviceLogix System User Manual - Manual (Page 25)

Publication RA-UM003B-EN-P - February 2010 25
Navigate the Function Block Editor Interface Chapter 2
Timing Diagnosis
The DeviceLogix Timing Diagnosis function block object determines
whether the occurrence of the expected event is within the preset
timing interval.
The following is an operation example:
The rising edge of the Trig Start input indicates the occurrence of a
Trig Start event. The rising edge of the Trig Finish input indicates the
occurrence of a Trig Finish event.
When the Trig Start event occurs, the Timing Diagnosis function block
is started. The internal timer starts timing from 0 as shown below.
Meanwhile, the function block reports the triggered status as the
output.
The events that occur in the illustration are as follows.
• If the Trig Finish event occurs before the Minimum Time, that is,
at the time slot (1), then the function block returns an early
finish status. If the occurrence of the Trig Finish event is within
the range of Min time and Min time + Range time, as shown in
time slot (2), then the Trig Finish event happens within the
expected timing slot. Therefore, a normal finish status is
returned. If no Trig Finish event occurs at the interval 0 and Min
time + Range time, then the Late Finish status is returned, as
shown in the time slot (4).
• Within the time interval 0 and Min time + Range time, if the Trig
Start event occurs again, that is as shown in the time slot (3),
then the Retrigger status is reported as the function block
output.
IMPORTANT
When data values are large, switching between REAL and DINT
data types may cause a minimal loss of accuracy. For example,
a value of 99999999 DINT will be rounded up to 100000000
REAL when you switch to a REAL data type and then back to a
DINT data type.