The daemons (background processes) make it possible to integrate PLC and fieldbus systems. Each daemon has access to a shared memory and a mailbox. The received data is stored in the shared memory. Your pvserver can easily read this shared memory. Using the mailbox you can send data to the field.
Usage of daemons:
./protocol_client config.ini
Within the ini file all necessary parameters for communication is provided. An example for each daemon is available also.