The PdServ library provides process data communication mechanisms for Linux realtime applications in user space (i. e. using RT PREEMPT). The main focus is placed on providing a process-data interface without interfering realtime operation. The library is a prerequisite for EtherLab 2.0, but can also be used independently. It implements the MSR protocol, so Testmanager, DLS or any application based on PdCom can act as a client.