Programming manual M238 | 3 MB - BERGER - POSITEC

Controller States and Behaviors
Controller States and Output Behavior
Introduction
The Modicon M238 Logic Controller defines output behavior in response to
commands and system events in a way that allows for greater flexibility. An
understanding of this behavior is necessary before discussing the commands and
events that affect controller states. For example, typical controllers define only two
options for output behavior in stop: fallback to default value or keep current value.
The possible output behaviors and the controller states to which they apply are:
Managed by Application Program
Keep Current Values
Set All Outputs to Default
Initialization Values
Output Forcing
Managed by Application Program
Your application program manages outputs normally. This applies in the RUNNING
and RUNNING with External Error states.
Keep Current Values
You can select this option by choosing Keep current values in the Behaviour for
outputs in Stop dropdown menu of the PLC settings sub-tab of the Controller
Editor. To access the Controller Editor, right-click on the controller in the device tree
and select Edit Object.
This output behavior applies in the STOPPED and HALT controller states. Outputs
are set to and maintained in their current state, although the details of the output
behavior varies greatly depending on the setting of the Update IO while in stop
option and the actions commanded via configured fieldbuses. Refer to Controller
States Description (see page 49) for more details on these variations.
Set All Outputs to Default
You can select this option by choosing Set all outputs to default in the Behaviour
for outputs in Stop dropdown menu of the PLC settings sub-tab of the Controller
Editor. To access the Controller Editor, right-click on the controller in the device
tree and select Edit Object.
This output behavior applies in the STOPPED and HALT controller states. Outputs
are set to and maintained in their current state, although the details of the output
behavior varies greatly depending on the setting of the Update IO while in stop
option and the actions commanded via configured fieldbuses. Refer to Controller
States Description (see page 49) for more details on these variations.
54 EIO0000000384 04/2012