The Modicon M241 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.
The possible output behaviors and the controller states to which they apply are:
Managed by
Hardware
Software
Your application program manages outputs normally. This applies in the RUNNING and RUNNING with External Error Detected states.
Select this option by choosing . To access the Controller Editor, right-click on the controller in the Devices tree and select .
This output behavior applies in the STOPPED controller state. It also applies to CAN bus in the HALT controller state. Outputs maintain their state, although the details of the output behavior vary greatly depending on the setting of the option and the actions commanded via configured fieldbusses. Refer to Controller States Description for more details on these variations.
Select this option by choosing . To access the , right-click on the controller in the Devices tree and select .
This output behavior applies:
when the controller is going from RUNNING state to STOPPED state.
if the controller is going from RUNNING state to HALT state.
after application download.
after reset warm/cold command.
after a reboot.
It also applies to CAN bus in the HALT controller state. Outputs maintain their state, although the details of the output behavior vary greatly depending on the setting of the option and the actions commanded via configured fieldbusses. Refer to Controller States Description for more details on these variations.
The outputs driven by a PTO, PWM, FreqGen, and HSC expert functions will not apply the default value.
This output state applies in the BOOTING, EMPTY (following power cycle with no boot application or after the detection of a system error), and INVALID_OS states.
In the initialization state, analog, transistor, and relay outputs assume the following values:
For an analog output: Z (high impedance)
For a fast transistor output: Z (high impedance)
For a regular transistor output: 0 Vdc
For a relay output: Open
This output state applies when downloading or when resetting the application. It applies at the end of the download or at the end of a reset warm or cold.
The software are the initialization values of outputs images (%I, %Q, or variables mapped on %I or %Q).
By default, they are set to 0 but it is possible to map the I/O in a GVL and assign to the outputs a value different than 0.
The controller allows you to force the state of selected outputs to a defined value for the purposes of system testing, commissioning, and maintenance.
You are only able to force the value of an output while your controller is connected to EcoStruxure Machine Expert.
To do so, use the command in the menu.
Output forcing overrides other commands to an output irrespective of the task programming that is being executed.
When you logout of EcoStruxure Machine Expert when output forcing has been defined, you are presented with the option to retain output forcing settings. If you select this option, the output forcing continues to control the state of the selected outputs until you download an application or use one of the Reset commands.
When the option , if supported by your controller, is checked (default state), the forced outputs keep the forcing value even when the controller is in STOPPED state.
The output you wish to force must be contained in a task that is currently being executed by the controller. Forcing outputs in unexecuted tasks, or in tasks whose execution is delayed either by priorities or events has no effect on the output. However, once the task that had been delayed is executed, the forcing takes effect at that time.
Depending on task execution, the forcing could impact your application in ways that may not be obvious to you. For example, an event task could turn on an output. Later, you may attempt to turn off that output but the event is not being triggered at the time. This would have the effect of the forcing being apparently ignored. Further, at a later time, the event could trigger the task at which point the forcing would take effect.
The outputs driven by a PTO, PWM, FreqGen, and HSC expert functions cannot be forced.
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