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PROFIBUS Communication DECS-250
4. Select modules from the GSD file to be part of the data exchange. Selecting the cyclic parameters is
recommended. The cyclic parameters are comprised of the first 12 instances in the PROFIBUS
parameters table (Table 29-6). Instances 1 through 5 consist of 25 float types. Instances 6 through 12
consist of 9 UINT8 types.
5. Set each selected module to an address in the master's memory bank.
6. Compile and download the configuration to the master before going online.
When the PROFIBUS network is initialized, the master connects to each slave checking for address
mismatches and sending configuration data. The configuration data is sent so that the master and slave
agree on the data exchange to occur. Then, the master begins polling each slave in a cyclic order.
It is not possible to write a portion of an instance by specifying a length
smaller than the size of the instance. To modify a single parameter,
read the entire instance, update the desired parameter, and write the
entire instance back to the device.
PROFIBUS Parameters
PROFIBUS parameters are listed in Table 29-6. Instances with names ending in “cyclic” are automatically
transmitted at a periodic rate. All other instances are acyclic and transmitted only when requested by the
PLC.
Table 29-6. PROFIBUS Parameters
Excitation Current Setpoint
GG
Excitation Voltage Setpoint
GG
Synchronizer Metering
Cyclic
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