FC 300 Profibus
How to Access FC 300 Parameters
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
Service
Read
Write
Data
transport
Initiate
Abort
Alarm
Master type
read data
from slave
write data
to slave
read and
write data
open a
connec-
tion
close a
connection
Master Class 1
yes
yes
yes
-
-
-
Master Class 2
yes
yes
yes
yes
yes
-
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:
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