Configuration of the UniPi module

A Unipi Neuron/Axon consists of small computer running a GNU/Linux and HW IO modules (see inner diagram for Neuron and Axon). These modules offer different functionality based on the IOs they present. For example digital inputs can act as Direct Switches, analog inputs can measure different quantities, digital outputs can output PWM and so on. Any output can have a default value, which applies right after powering up the PLC, way before the finishing the boot up sequence of the operating system. This configuration also applies to the Unipi Extensions, albeit they don't run any OS.


All of these configurations are OS-independent and are permanently stored into the modules. If you receive an used UniPi unit, the best approach is to save a blank new configuration to overwrite possible unwanted settings.

In Mervis, the configuration is pushed via context menu of the connected prototype. Right click on the prototype name in the Left Panel and in the context menu click on “UniPi - Configure Module”.

You can run into error, which says “Selected channel does not exist in the PLC”:

This is caused by calling Configure Unipi Module on a channel, which isn't configured in the PLC yet. Typically this happens when you create channel, add Library Device and call the Configure Unipi Module right away. The MervisRT still doesn't know anything about this channel, because it will receive the information with next Deploy of the solution. Simple Deploy after creating channel will fix this.

During the configuration, the PLC will be switched to “Commissioning mode”, which means it will stop running the previously deployed solution. After the configuration, the PLC will return to its previous state. Make sure, that the connected technology is prepared for this blackout.

After confirming the dialog, the MervisIDE will start configuring the modules:

Once the configuration finishes, the PLC will switch back to its previous state and you can resume the work.