GE Industrial Solutions AF-600 FP Profibus DP - Manual (Page 22)

4 How to Control the Frequency Converter
4.1 PPO Types
The PROFIBUS profile for frequency converters specifies a number of communication objects (Parameter Process data Objects, PPO), which are suitable for data
exchange between a process controller, such as a PLC, and frequency converters. All PPOs are defined for cyclic data transfer (i.e. DP V0), so that process data
(PCD) and parameters (PCA) can be transferred from the master to the slave and vice versa. The figure below shows the PPO types available for the GE AF-650 GP
& AF-600 FP drives..
PPO types 3, 4, 6, 7 and 8 are pure process data objects for applications requiring no cyclic parameter access. The PLC sends out process control data, and the
frequency converter then responds with a PPO of the same length, containing process status data. The first two bytes of the process data area (PCD 1) comprise
a fixed part present in all PPO types. The next two bytes (PCD 2) are fixed for PCD write entries (par. PB-15 PCD Write Configuration [1]), but configurable for PCD
read entries (par. PB-16 PCD Read Configuration [1]). In the remaining bytes, from PCD 3 and on, the process data can be parameterised with process signals from
the list on par. PB-23 Parameters for Signals.
Select the signals for transmission from the master to the frequency converter in par. PB-15 PCD Write Configuration (request from master to the frequency
converter). Select the signals for transmission from the frequency converter to the master in par. PB-16 PCD Read Configuration (response: Drive -> master).
PPO types 1, 2 and 5 consist of a parameter channel and process data. The parameter channel can be used for reading and/or updating of parameters (succes-
sively). Alternatively, for better utilisation of I/O and thus PLC capacity, parameters can be accessed via DP V1, in which case a pure process data object should
be chosen (PPO type 3, 4, 6, 7 or 8).
The choice of PPO type is made in the master configuration, and is then automatically recorded in the frequency converter. No manual setting of PPO types in
the frequency converter is required. The current PPO type can be read in par. PB-22 Telegram Selection.
In addition, all PPO types can be set up as word consistent or module consistent. For GE AF-650 GP & AF-600 FP drives, the process data area can be word or
module consistent, whereas the parameter channel must always be module consistent. Module consistent data is transmitted as sets of interrelated words
transferred simultaneously between the PLC program and the frequency converter. Word consistent data is transmitted as individual independent words between
the PLC and the frequency converter.
Selection [1] Standard telegram 1 is equivalent to PPO type 3.
AF-650 GP/AF-600 FP Profibus DP Operating Instructions
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