Communication
6.3 Acyclic Communication
Control Units CU240S
140
Operating Instructions, 07/2008 - FW 3.2, A5E00766042B AD
6.3
Acyclic Communication
Overview of Acyclic communication
The content of the transferred data block corresponds to the structure of the acyclic
parameter channel according to PROFIdrive Profile, version 4.1
(http://www.profibus.com/organization.htm (Page 128))
Acyclic data transfer mode allows in general:
● Large quantities of use data (up to 240 bytes) to be exchanged. A parameter
request/response must fit in a data block (max. 240 byte). The requests/responses are
not split-up over several data blocks.
● Transmission of complete arrays or parts of them, or the entire parameter description.
● Transmission of different parameters in one access (multi-parameter requests).
● To read out the profile-specific parameters by an acyclic channel
● Acyclic data transmission in parallel to cyclic data transmission.
Always just one request is being processed at a time (no pipelining). No spontaneous
messages will be transmitted.
Acyclic communication via PROFIBUS DP (DPV1)
The PROFIBUS DP extensions DPV1 include the definition of an acyclic data exchange.
It allows simultaneous accessing by other PROFIBUS masters (class 2 master, e.g. start-up
tool).
Conversion of extended PROFIBUS DP functionality
The different masters, or different modes of data exchange, are represented by appropriate
channels in the SINAMICS G120 range of inverters:
● Acyclic data exchange with the class 1 master uses the DPV1 functions READ and
WRITE (with data block 47 (DS47)).
● Acyclic data exchange using a SIEMENS start-up tool (class 2 master) (e.g. STARTER).
The start-up tool can acyclically access parameter and process data in the inverter.
● Acyclic data exchange with a SIMATIC HMI (second class 2 master). The SIMATIC HMI
can acyclically access parameters in the inverter.
● Instead of a SIEMENS start-up tool or SIMATIC HMI, an external master (class 2 master)
as defined in the acyclic parameter channel according to PROFIdrive Profile version 4.1
(with DS47) can access the inverter.
