Exceptions

Exceptions are runtime conditions that the device continually checks that might indicate improper behavior of the axis or operation outside of an allowable range. An exception can result in an alarm, a minor fault, or a major fault, depending on how the associated Axis Exception Action has been configured – an exception can even be configured to be ignored. The device clears exceptions when the underlying exception condition is no longer present.

Axis Test Mode

Axis Test Mode Enabled axes using Controller Loopback do not simulate controller-generated Axis Exceptions.

Exception Actions

For each exception, the motion axis can be programmed for a variety of actions using the Exception Action attribute. Exception Actions range from generating a major fault that results in the stopping of the axis all the way to taking no action at all. The CIP Axis Faults attribute allows the controller to have immediate access to any exceptions that have been configured to generate a major or minor fault. The CIP Axis Alarms attribute allows the controller to have immediate access to any exceptions that have been configured to be reported as alarms.

Alarms

Alarms are runtime exception conditions for which the device is to take no action other than to report as an alarm. Alarms and warnings, therefore, are synonymous. On a given device product, some exception conditions may not be able to be reported as an alarm without any associated action; for example, an IPM fault in which the power module automatically shuts off without software intervention. Alarm conditions are automatically cleared when the underlying exception condition is no longer present.

Axis Test Mode

Axes with the Test Mode attribute set to Enabled and that are configured for Controller Loop Back simulate these alarms.

Faults

Faults can be initialization faults, configuration faults, safety faults, module faults, group faults, motion faults, or runtime exception conditions that the axis has been configured to regard as a fault. Fault conditions can occur in either the controller or the motion device. If a runtime fault occurs during an operational state, for example, Running or Testing, it will result in the device stopping (or aborting) all axis motion, either automatically or programmatically. Fault conditions ultimately transition the axis state to the Faulted state. A Fault that results from an exception condition is latched, and does not clear when the exception condition clears. A fault can only be cleared with a Fault Reset. If the fault condition is classified as an 'unrecoverable fault', only a power cycle or a device reset can clear the fault condition.

Axis Test Mode

Axes with the Test Mode attribute set to Enabled and that are configured for Controller Loop Back simulate these faults.

Start Inhibit Behavior

A Start Inhibit is a condition that inhibits the axis from starting, that is, transitioning to the Starting state for enabled axis operation. This condition does not generate an exception if a start attempt is made. If the circumstances that led to the Start Inhibit are no longer present, the device clears the start inhibit condition, returning the axis to the Stopped State.

If the axis is in the Start Inhibit state, it indicates that one or more conditions are present that helps prevent the axis from transitioning to enabled operation. The Start Inhibits attribute reports the specific condition that is inhibiting the axis.