Fieldbus control through the embedded fieldbus interface (EFB) 60711Fieldbus control through theembedded fieldbus interface(EFB)What this chapter containsThe chapter describes how the drive can be controlled by external devices over acommunication network (fieldbus) using the embedded fieldbus interface.System overviewThe drive can be connected to an external control system through a communicationlink using either a fieldbus adapter or the embedded fieldbus interface.The embedded fieldbus interface supports the Modbus RTU protocol. The drivecontrol program can handle 10 Modbus registers in a 10-millisecond time level. Forexample, if the drive receives a request to read 20 registers, it will start its responsewithin 22 ms of receiving the request – 20 ms for processing the request and 2 msoverhead for handling the bus. The actual response time depends on other factors aswell, such as the baud rate (a parameter setting in the drive).The drive can be set to receive all of its control information through the fieldbusinterface, or the control can be distributed between the embedded fieldbus interfaceand other available sources, for example, digital and analog inputs.
