Master profile and structure of a slave

Master profiles

The AS-i system operates according to the master-slave principle. The AS-i master controls exchange of data with a maximum of 31 slaves. The specifications of the AS‐i master establish a distinction between the masters depending on the number of services offered (definition of profiles). Three types of master profile exist: (M0, M1, M2). AS-i specifications clearly define the functions that a master must possess for a given profile.

The AS-i standard defines several service levels offered by the master:

Profile M0 - Minimum Master: the master exchanges data with the different slaves. The master only proposes the configuration of slaves connected to the bus on power-up, and only for input/output exchanges.
Profile M1 - Full Master: this profile covers all the functions defined in the AS‐i master specifications,
Profile M2 - Reduced Master: this profile corresponds to the operating functions for profile M0 with a slave parametering option.

For the TBX SAP 10, the profile used is M2, with in addition, the possibility of sending diagnostics data to the PLC.

Structure of an AS-i Slave

The AS-i slave is equipped with an integrated circuit for connection to the AS-i bus. The integrated circuit has:

4 configurable data inputs,
4 configurable data outputs,
4 slave parameter states.

The other operating parameters, configuration data with I/O allocation, as well as identification and address codes are saved in a non-volatile memory.

The figure below shows the structure of an AS-i slave.

Description of Constituent Elements

The table below shows the different elements that make up the structure of a slave address.

Element	Description
I/O data	The outputs are designed for automation components and are transmitted by the master AS-i to the AS-i slave. The input values are stored by the AS‐i slave and made available to the master.
Parameters	AS-i slave parameter states enable the AS-i master to transmit the values that will not be interpreted as input/output data. These parameters can be used for controlling and switching internal operating modes of sensors or actuators. Examples: motor-starter: slow or fast rotation speed, run, stop, etc. proximity detectors: range, background suppression, etc. These parameters may be used to correct a calibration dimension during the different operating phases. This function can be performed on slaves with a built-in AS-i connection on the condition that they support this function. Only a master with profile M1 or M2 can modify these parameters.
Configuration/Identification	The input/output configuration (or I/O code) defines the AS-i slave data used as inputs, outputs, or as bi-directional outputs. The I/O configuration (4 bits) is defined by the manufacturer of the slave and is specified in the slave's documentation. The type of an AS-i slave (or Identification Code) is defined by the I/O configuration but also by an identification code. The latter is coded by each slave on 4 bits. It is also manufacturer-specific and mentioned in the documentation.
Address	At the time of delivery, the address for slaves is 0. So that data may be exchanged, the slaves must be programmed with an address between 1 and 31. The address 0 is reserved for specific functions.