Danfoss FC 300 Profibus Manual page 43

FC 300 Profibus
be used for general parameter access in the slaves. However, the acyclical connection is fixed, and cannot
be changed during operation.
Features of a Master Class 2 Connection
-
Initiate / Abort acyclical connection
-
Acyclical read/write from and to parameters
The master class 2 acyclical connection is typically used for configuration or commissioning tools for easy
access to each parameter in any slave in the system. The acyclical connection can be dynamically established
(Initiate) or removed (Abort) even when a master class 1 is active on the network.
Services Overview for FC 300
Master type
Master Class 1
Master Class 2
Principle of Data Exchange by PROFIBUS DP V1
In a DP cycle the master class 1 (MC1) will first update the cyclical process data for all slaves in the system.
The MC1 can then send one acyclical message to one slave. If a master class 2 (MC2) is connected, the MC1
will hand over the bus rights to MC2, which will then be permitted to send one acyclical message to one
slave. The token is then handed back to the MC1, and a new DP cycle begins.
MC : Master Class
C1...Cn: Cyclical data
AC1: Acyclical data Master Class 1
AC2: Acyclical data Master Class 2
PROFIBUS DP services are activated via specific Service Access Points (SAP). For acyclical communication,
the following SAP are specified:
How to Access FC 300 Parameters
Service
Read Write
read data write data
from slave to slave
yes yes
yes yes
MG.33.C2.02 - VLT is a registered Danfoss trademark
Data Initiate
transport
read and open a
write data connec-
tion
yes -
yes yes
Abort Alarm
close a
connection
- -
yes -
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