GE Industrial Solutions AF-600 FP Profibus DP - Manual (Page 42)

5.2.2 Features of a Master Class 1 Connection
- Cyclical data exchange (DP V0)
- Acyclical read/write from and to parameters
In general a master class 1 is used as the process controller (either PLC or PC-based), responsible for commands, speed reference, status of the application, etc..
The master class 1 acyclical connection can be used for general parameter access in the slaves. However, the acyclical connection is fixed, and cannot be changed
during operation.
5.2.3 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.
5.2.4 Services Overview for AF-650 GP & AF-600 FP drives
Master type Service
Read Write Data transport Initiate Abort Alarm
read data from
slave
write data to slave read and write data open a connection close a connection
Master Class 1 yes yes yes - - -
Master Class 2 yes yes yes yes yes -
5.2.5 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 network 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
AF-650 GP/AF-600 FP Profibus DP Operating Instructions
41
5