Abstract: A test unit for data communication networks is formed by placing one or more application modules between a front module and a rear module. The modules are secured together with a latching system and a bus structure provides for control and performance information transfers between modules. The front module may serve a user interface via a touch screen. In addition, the front module has a variety communication ports that provide for one or more remote user interfaces. Battery packs are located in the front module and the rear module for providing power to the test unit.

Abstract: A test unit for data communication networks is formed by placing one or more application modules between a front module and a rear module. The modules are secured together with a latching system and a bus structure provides for control and performance information transfers between modules. The front module may serve a user interface via a touch screen. In addition, the front module has a variety communication ports that provide for one or more remote user interfaces. Battery packs are located in the front module and the rear module for providing power to the test unit.

Abstract: The periodic axial movement of the rotary piston (6) is performed by a cam mechanism which has a cam surface (8) rotating around the piston axis and a cam follower (9) that is in functional connection with the cam holder. The relative position of the cam holder determines the piston stroke in the course of one revolution. In this arrangement, the drive shaft (5) can extend coaxially with the piston (6). In a particularly advantageous manner, the follower is pressed against the cam holder under spring pre-tension.