The Require Periodic Transitions option is used to test periodic Signals. When this option is activated, each transition must be no more than the specified Period Maximum after the previous transition or the test fails. The test is for the presence of transition data, not for its value. This period test is in addition to testing for any specified time tolerances.

Suppose a Transform is designed to output a transition pulse every 5 milliseconds. If a pulse is late or missing, the test fails. It doesn't matter if the value of the pulse varies or is constant.

In most cases, if a Transition on a numeric Signal has a value identical to the previous Transition, the Transition is considered redundant and MxVDev discards it. The Require Periodic Transitions option cannot be used on these signals unless the Transitions are Persistent. See Redundant and Persistent Transitions.

There are two ways to test periodic Signals:

At the Signal level, you can set the Require Periodic Transitions option and Period Maximum using the Pass/Fail Criteria tab in the Signal Properties.

At the DataBlock level, you can set the Check Transition Periodicity option and Period Maximum using the Pass/Fail Criteria tab in the DataBlock Properties.

If these options are set, each transition must be no more than the specified Period Maximum after the previous transition or the test fails. The DataBlock Properties override the Signal Properties. See Inheritance.

Periodic Message Signals

For message Signals, you can verify specific transition values and times (pattern matching) or check transition periodicity, but not both. Pattern matching for message Signals requires checking the contents and time of each message, and is incompatible with periodicity checking.

DataBlock Properties for a Message Signal

DataBlock Properties for a Message Signal

If you select Verify Value and Time of Transitions, the Message Order tab is displayed. If Ignore Message Order is checked, the order of the actual messages does not have to match the order of the expected messages to pass.

DataBlock Properties Message Order Tab

DataBlock Properties Message Order Tab

By default, the number of transitions must match exactly the number in the Expected Results pattern. However, you can specify a negative or positive tolerance to allow missing or extra transitions.

DataBlock Properties: Transition Count Tolerances

DataBlock Properties: Transition Count Tolerances

Related Topics:

Pass/Fail Judgment Overview

DataBlock Properties (Transition Count)

Automatic Message Transmission