This module gives access to the process image of the PLC.
The first two bytes of the entire process image of inputs and outputs are reserved as status, error and control bytes. These can not be accessed through the MicroPython API. The remaining bytes are user-defined message bytes and can be freely adapted by the application. The user can access them by using the functions plc.read() and plc.write().
The figure below shows the exchange of a message between the PLC and TM NPU using the process image.
General information on the process image and the content of the status, error and control bytes can be found in the TM NPU User Manual.
There is no prepared protocol implemented for message handling between the TM NPU and PLC, e.g. indicating whether the module is in a ready, busy or done state for a task, or whether the information was updated. If required, this would have to be realized by the application. Examples of how this can be implemented are available in the application example.