Siemens SINAMICS G110D, Operating Instructions Manual

Page: 158 / 224

Functions
6.11 Operation in fieldbus systems
SINAMICS G110D
158
Operating Instructions, 07/2016, FW V3.63, A5E36768472B AB
supply which provides power for the electronics inside the Inverter. No communications
takes place of this second cable.
In the diagram below an example is given of how the Manchester coded current pulses are
used for communicating data.
Image 6-23 AS-i communications using Manchester coding
Up to 31 standard slaves can be connected to the bus. This figure is doubled to 62 extended
A/B slaves where one of the communication bits from the master is used to allow two slaves
to share an address. When this is done the two slaves are referred to as A and B, and the
master communicates with each on alternate cycles.
The basic communication system of AS-i allows only 4 bits of digital data to be transferred
between master and slave. While this is sufficient for simple applications for which AS-i was
originally intended, more complex applications require more data such as analogue values or
serial transfers. To address this requirement version 3.0 of the AS-i standard introduced
‘combined transactions’ in which some of the data bits from the basic communications are
used to implement a serial interface capable of transferring both cyclic and acyclic data.