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Sercos defines how the actual value is recorded and how valid the set value is for processes from different products and manufacturers that are to be synchronized. Each device receives a data telegram with a particular transmission time delay that is appropriate to the device. Unlike other Ethernet bus systems, Sercos derives a general execution time directly from the bus. The device calibrates itself independently with the bus cycle by using the arrival of the MST while taking into account the transmission time in the bus during each bus cycle to generate and adjust the internal synchronizing mechanism. As a result, separate clocks are synchronized exactly without exchanging time data that overloads the bandwidth.
The Sercos master simply has to detect the line or ring transmission time and transmit data to each device together with a sum value that has been appropriately configured. Variations in the sum value can delay the stable synchronization signal.
Hence delaying the synchronization time or having to reconfigure the sum value, for example, can be prevented when connecting additional devices to the Sercos network which is operating in cyclical real-time (so-called “hot plugging”). The synchronization process ensures that cyclical and simultaneous synchronization of all connected devices is carried out independently of topology and of the quantity of devices in Sercos networks. The process itself is quick, robust and simple to apply. Using the described process, Sercos is able to achieve synchronization accuracy of less than 20ns and synchronicity of less than 100ns. Given that individual Sercos networks can be connected to a network system based on a C2C profile (C2C=Controller to Controller), fully synchronized network structures can be formed without limiting synchronization performance.
Increased accuracy of the transmission ensures that we can implement the most challenging applications.