Abstract: Volume flows of liquids in capillary tubes of chromatographic separation columns for analytical liquid measuring technology are controlled. The volume flows are derived from a liquid transport, i.e., pump arrangement, which transports a total flow to a flow splitter that divides the total flow into an excess flow in an excess path and a working flow in a working path. A controller for the working flow responds to at least one working sensor. The working sensor senses the mass flow rate of the working flow and/or the pressure in the working path which is coupled with the working sensor or the pressure differential in conduits for the excess and working flows.

Abstract: A network bus for interconnecting a plurality of medical devices is described in which the devices are provided with modules adapted to communicate along the bus. Some of the devices are capable of assuming control over the bus with network master modules. A self-configuring capability is provided with which several network master capable medical devices automatically determine which network master is to take over control over the network bus and each individually is capable of controlling and operating the network. Each network master capable device has an extended network management module with which automatic master selection is achieved. This is done by monitoring or observing network communications for particular objects. Once such an object has been detected, a network master capable device is automatically selected to take over control on the basis of its priority.