Control; Ppo Types - Danfoss VLT Midi Drive FC 280 Programming Manual

Control

4 Control

4.1 PPO Types

The PROFIBUS profile for frequency converters specifies a
number of communication objects (parameter process data
objects, PPO). The PROFIBUS profile for frequency
4 4
converters is suitable for data exchange between a process
controller (for example PLC) and a frequency converter. All
PPOs are defined for cyclic data transfer (DP-V0) for
transferring process data (PCD) and parameters (PCA) from
the master to the slave, and conversely.
Pure process data objects
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.
Illustration 4.1 shows the available PPO types:
•
PCD 1: The first 2 bytes of the process data area
(PCD 1) comprise a fixed part present in all PPO
types.
•
PCD 2: The next 2 bytes are fixed for PCD write
entries (see parameter 9-15 PCD Write Configu-
ration [1]), but configurable for PCD read entries
(see parameter 9-16 PCD Read Configuration [1]).
•
PCD 3–10: In the remaining bytes, the process
data can be parameterized with process signals,
see parameter 9-23 Parameters for Signals.
The setting in parameter 9-15 PCD Write Configuration
determines the signals for transmission (request) from the
master to the frequency converter.
12
PROFIBUS DP
The setting in parameter 9-16 PCD Read Configuration
determines the signals for transmission (response) from the
frequency converter to the master.
Parameter channel and process data
PPO types 1, 2, and 5 consist of a parameter channel and
process data. Use the parameter channel for reading
and/or updating parameters (successively). Alternatively, for
better utilization of I/O and PLC capacity, access
parameters via DP-V1. To access via DP-V1, select a pure
process data object (PPO type 3, 4, 6, 7, or 8).
Select the PPO type in the master configuration. The
selection is automatically recorded in the frequency
converter. No manual setting of PPO types in the
frequency converter is required. Read the current PPO type
in parameter 9-22 Telegram Selection. The setting [1]
Standard telegram 1 is equivalent to PPO type 3.
In addition, all PPO types can be set up as word-consistent
or module-consistent. The process data area can be word-
or module-consistent, whereas the parameter channel
must always be module-consistent.
•
•
Danfoss A/S © 05/2016 All rights reserved.
Word-consistent data is transmitted as individual,
independent words between the PLC and the
frequency converter.
Module-consistent data is transmitted as sets of
interrelated words transferred simultaneously
between the PLC and the frequency converter.
MG07F102