Communication / PROFIBUS 09.2008
6SE7087-6QX70 (Version AK) Siemens AG
8.2-12 Compendium Motion Control SIMOVERT MASTERDRIVES
8.2.2.3 Acyclical master class 1, automation (PLC)
Acyclical communication between the DP master Class 1 (DPM1) and
the DP slaves takes place via supplementary service access point 51. In
a service sequence, the DPM1 establishes a link to the slave, this link
being designated MSAC_C1. Establishment of this link is closely related
to the link for cyclical data transfer between the DPM1 and the slaves.
Once a link has been established, the DPM1 can conduct cyclical data
transfer via the MSCY_C1 link and, at the same time, acyclical data
transfer via the MSAC_C1 link.
The MSAC_C1 channel enables READING and WRITING of any of the
data blocks in the slave. These data blocks are accessed with the
PROFIBUS functions, DDLM_Read and DDLM_Write.
For processing parameters, the CBP supports a data block with the index
100 in slot 2. Because the parameters can only be altered infrequently in
comparison to the process data, the parameter area of the telegram can
be removed from the fast cyclical channel in order to save bus resources.
With the CBP2, version V2.21 and later, a class 1 master automation
(PLC) can also utilize acyclic parameter access according to PROFIdrive
V3, cf. Section 8.2.4 "PROFIdrive V3: Acyclic parameter accessing with
data block 47".
MSAC_C1 channel
NOTE
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