Control; Ppo Types - Danfoss VLT PROFIBUS DP MCA 101 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
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 (that is, DP V0), so
that process data (PCD) and parameters (PCA) can be
transferred from the master to the follower and vice versa.
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 (PCD 2) are fixed for PCD
write entries (see parameter 9-15 PCD Write
Configuration [1]), but configurable for PCD read
entries (see parameter 9-16 PCD Read Configu-
ration [1]).
•
PCD 3-10: In the remaining bytes, from PCD 3
and on, the process data can be parameterised
with process signals, see
parameter 9-23 Parameters for Signals.
The signals for transmission from the master to the
frequency converter are determined by the setting in
parameter 9-15 PCD Write Configuration (request from
master to the frequency converter).
The signals for transmission from the frequency converter
to the master (response from the frequency converter to
master) are determined by the setting in
parameter 9-16 PCD Read Configuration .
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 of parameters (successively). Alternatively,
for better utilisation of I/O and thus PLC capacity, access
parameters via DP V1, by selecting 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 9-22 Telegram Selection. The setting [1] Standard telegram
1 is equivalent to PPO type 3.
MG37G102
Programming Guide
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 © Rev. 05/2014 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.
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