Promicon Systems

Drive network

The backbone of the VariMotion system is the vNET drive network. The network consists of a modular configurable head module, which centrally controls all activities and connects it with the controller modules to activate the motors.

Central administration

Parameter and firmware of the control modules are saved in the head module and are re-loaded automatically when switching on. This especially facilitates the device exchange, because there is no need for special expertise or a computer with appropriate software. Furthermore the system diagnosis is eased, because signals of the control modules are recorded in the head module and chronicled in a diagnostic logbook.


The vNET was developed with great care of a high transmission rate and short reaction time, because only in this way the high dynamics of modern servo drives can be fully developed. The time for bi-directional data traffic between 2 participants is under 3 µs at the vNET, unidirectional data transfer requires less than 2 µs. In comparison, the minimal frame length at a 100 Mbit Ethernet is already more than 5 µs.


The key for the precision of the networked control engineering lies in the isochronous timing of the data transfer. Here, the head module sends special telegrams in a fixed grid and the connected modules derive the instants of their activities from them. The timing inaccuracies of these synchronization telegrams are called jitter. The value achieved by the vNET is much better than the value of other systems.


A very important aspect in practical use is the high robustness of the overall system against electromagnetic influences. As the wiring is usually installed in an EMV-critical environment and the causes of impairing often are very difficult to find, this point is of essential importance to achieve a high availability and reliability.