VARAN Bus key data

The optimized real-time Ethernet bus system for the highest performance demands

By using the Manager-Client principle, collisions are avoided. The VARAN bus provides highest speed, shortest cycle time and minimum synchronicity jitter. In addition, it offers the unique possibility of asynchronous direct access.  

Data packets are repeated within the cycle until a valid acknowledgment is received. Therefore, the validity of all data is guaranteed at the end of each cycle. This permanent testing of data validity, even for bus cycle times less than 100 µs, is only possible through use of the small VARAN data frames (1 – 128 bytes).



Hard real-time Cycle times < 100 µs, jitter < 100 ns - each instruction is immediately confirmed by the receiver

High data reliability and
error tolerance

Unacknowledged messages are repeated within the same bus cycle
Flexible network topology Modular machine structures using star, line or tree topologies
Economic Costs comparable to a field bus connection through the use of inexpensive FPGAs for managers and clients
Open standard

The VARAN BUS USER ORGANIZATION (VNO) manages the open VARAN bus technology


Further Advantages at a Glance

Automatic addressing Minimal network administration costs


High data transfer rates - higher scan rates - higher performance - increasing quality
Deterministic behavior Bus participants are accessed in each bus cycle at exactly the same time
Direct access Fast asynchronous direct access at any time
Hot plug capability

Participants can be added or removed during operation

Protocol completely
implemented in the hardware
No additional load on the CPU
Simple implementation Also in small sensors/actuators
Synchronization over PLL Distributed clocks according to IEEE 1588 are not required
Multi Manager capable RT-Networking of several autonomously operating systems
Tunneling of standard Ethernet

Standard TCP/IP communication is possible even with the shortest cycle times

Bus and power supply in one
Simple signal and power transmission through VNO- certified connectors and cables is possible

CANopen® mapping on the

Simple connection to existing CANopen® devices

Analysis and service made

With comfortable diagnostic and service tools


Performance data

Bus cycle times
< 100 µs
< 100 ns
Isochronous access time
1 Byte r/w
2,18 µs
16 Byte r/w (1 drive)
5,05 µs
Asynchronous direct access
128 Byte r/w
< 25 µs

Portable to Gigabit Ethernet without protocol changes