The C35, C65, and C105 come in three different configurations: BASIC A, PLC B, and PLC C. The different configurations offer increasing options for controlling and communicating with the unit.
While BASIC A is the simplest machine with limited control options, PLC C is the most sophisticated one, including additional functionalities and setups. As an addition to the PLC C configuration, a PLC D sensor upgrade kit can be bought. The PLC D includes two humidity sensors for internal measurements of the process air.
You can find more detailed information regarding the different configurations for each dehumidifier range in the following datasheets: