PROFIBUS DP-Master

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5.3 Functionality of the FSPMM-Task (Layer 7)
Profibus DP provides the following functionality with its layer 7 part, which is implemented within the
FSPMM_task:
• Cyclic Data Transfer
• Acyclic Data Transfer DP V1 Class 1
• Configuration of Inputs and Outputs at Slaves
• Alarm Processing
• Diagnostics
5.3.1 Cyclic Data Transfer
Cyclic data transfer is the main task of a field bus system. In Profibus DP, this functionality is located
in level DP V0. The main packets for cyclic data transfer are:
Packets for Cyclic Data Transfer
Section
Packet Name
6.1.8 PROFIBUS_FSPMM_CMD_GET_INPUT_REQ/CNF - Get new Input
6.1.7 PROFIBUS_FSPMM_CMD_SET_OUTPUT_REQ/CNF – Set new Output
Table 35: Packets for Cyclic Data Transfer
5.3.1.1 Description of Processes during Cyclic Data Transfer
The most important prerequisite for cyclic data transfer is, that the operation mode is OPERATE.
In state CLEAR only a restricted cyclic data transfer is possible, in the other states no cyclic data
transfer at all is performed.
For example, a data transfer from the master to the slave using the
PROFIBUS_FSPMM_CMD_SET_OUTPUT_REQ/CNF – Set new Output packet works in the following
way:
• The master sends an SRD request with a variable data field length containing the output data to
the slave.
• Immediately the slave will send back an SRD response containing its input data.
The number of available input and output channels is defined at the configuration during system startup.
This configuration is done as a part of the processing of the bus parameter set, for more
information see
• Section 4.2.4 Detailed Description of Slave Parameters, especially 4.2.4.15 Cfg_Data_Len and
4.2.4.16 Cfg_Data
• Section 6.1.1 PROFIBUS_FSPMM_CMD_APP_REG_REQ/CNF – Application Register
• Section 6.3.14 PROFIBUS_DL_CMD_SET_VALUE_BUS_PARAMETER_SET_REQ/CNF -
Load the Bus Parameter Set
PROFIBUS DP-Master |
DOC061001API12EN | Revision 12 | English | 2010-12 | Released | Public © Hilscher, 2006-2010