Phoenix Contact 2701027 NLC-050-024D-06I-04QTP-00A nanoLine Base Unit 24ßV/DC / PNP 2701027 Data Sheet
Product codes
2701027
Getting Started and Tutorial
2373_en_B
PHOENIX CONTACT
2-21
Figure 2-16
Sample status flow chart variation 2
2.5.3
Diagnostic Flow Chart
A diagnostic flow chart looks for any project-stopping errors (for example, an Emergency
Stop) and current process actions, which usually originate in the auto-mode flow chart(s).
When an action is in progress, the diagnostic flow chart looks for faults. These faults can be
improbable, probable, and those that indicate an error when an event doesn’t occur after a
certain period of time. If a fault occurs, the diagnostic flow chart displays a message, or turns
necessary outputs ON or OFF (for example, turn on an LED to indicate a specific error, turn
off a motor to stop a given action), which can vary per error, application requirements, and
safety regulations.
Flow then goes back to the next decision block to check if the next error occurred for that
same action. Once the flow chart has checked all possible error conditions for a given
action, the flow chart checks to see if the next action is occurring.
Whether or not an error occurred, the flow chart checks to see if an operator cleared a fault
that may have occurred. If so, the flow chart clears the existing error message and turns off
any error indicators.
Figure 2-17 illustrates a diagnostic flow chart for a greenhouse application. Although it does
not show all possible error conditions, it provides an excellent example of the concepts
discussed above.