52 Unidrive M SI-PROFIBUS User Guide
Issue Number: 3
9 Non-cyclic data
9.1 What is non-cyclic data?
Non-cyclic data allows access to any parameter without the need to use cyclic data
transfers. This is particularly useful when accessing many different parameters for set-
up or archiving of drive settings. The method to use non-cyclic data on the SI-
PROFIBUS is by using DP-V1 Parameter Access.
Non-cyclic data using the DP-V1 non-cyclic channel must not be confused with the non-
cyclic over cyclic method as used with the CT non-cyclic and PPO 4 word modes.
9.1.1 DP-V1 Parameter Access
Non-cyclic data is transmitted after all the cyclic data within the PROFIBUS-DP cycle,
depending on the length of the non-cyclic data, this may take several cycles to
complete.
9.2 Configuration using non-cyclic data
The SI-PROFIBUS can be configured using the DP-V1 Parameter Access channel
non-cyclic data. This is useful when using a master controller to configure the drive;
when a drive is initialized only the node address S.01.004 needs to be set manually.
The master can now use the desired mode to set-up the remainder of the parameters.
The configuration parameters for the slot in which the SI-PROFIBUS is located can be
accessed in S.01.ppp and MM.ppp. Any changes made to the configuration
parameters will not take effect until the SI-PROFIBUS has been reset.
SI-PROFIBUS can be reset by writing a value of 1 to Pr MM.007. A brief interruption in
PROFIBUS-DP communications may be seen while the reset sequence is in progress.
9.3 SI-PROFIBUS non-cyclic overview
The PROFIBUS specification allows for the standard cyclic process data and the
additional acyclic parameter data to be transmitted in the same bus cycle.
The DP-V1 message is contained within the acyclic part of the PROFIBUS-DP cycle
and uses the slave node address to access the parameter channel.
For further details of the SI-PROFIBUS functionality refer to the official PROFIBUS
website at www.profibus.com
The following services will be supported:
• Class 1 Master Read and Write
• Class 2 Master Read and Write
• Class 2 Master Initiate Connection
• Class 2 Master Abort Connection
A class 1 master must be in data exchange with the slave before it can perform a
request via the DP-V1 channel. A class 2 master must initiate the connection with the
slave before sending the DP-V1 message, likewise it must then abort the connection
when it is no longer required.
SI-PROFIBUS supports the simultaneous connection to one class 1 master and one
class 2 master.
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