How To Control The Frequency Converter; Pdo Communication; Process Data - Danfoss MCA 124 Operating Instructions Manual

How to Control the Frequenc...

6 How to Control the Frequency Converter

6.1 PDO Communication

The DS402 profile for frequency converters specifies a
number of communication objects (SDOs). SDOs are
suitable for data exchange between a process controller,
for example a PLC, and frequency converters. Some SDOs
are defined for cyclic data transfer, so that process data
(PCD) can be transferred from the controller to the slave
and vice versa. PDOs are used for cyclic data, a subset of
the SDOs are PDO mappable.
PDO 23 is 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 transmit PDO containing process status
data. In the Danfoss EtherCAT interface all PDOs are free
selectable. The first two words of the process data area
(PCD 0 and PCD1) are set to a default value at factory, but
can be changed.
Select the signals for transmission from the master to the
frequency converter in 12-21 Process Data Config Write
(request from master to the frequency converter). Select
the signals for transmission from the frequency converter
to the master in (response: FC ⇒ master).
The EtherCAT option has only one PDO available - PDO 23.
The PDO 23 is flexible in size, so that it can be adjusted to
fit all needs (max. 10 PCDs). The selection is made in the
master configuration, and is then automatically
downloaded to the frequency converter during the
transition from Init to Pre-Op. No manual setting of PPO
types in the frequency converter is required.
Selection [1] Standard telegram 1 is equivalent to PDO 23.
Receive PDOs (PLC Drive)
PCD 0 PCD 1
PDO 23
CTW REF
Transmit PDOs (Drive PLC)
PCD 0 PCD 1
PDO 23
STW MAV
Illustration 6.1
MCA 124 EtherCAT Operating Instruction

6.2 Process Data

Use the process data part of the PDO for controlling and
monitoring the frequency converter via the EtherCAT.
6.2.1 Process Control Data
Process data sent from the PLC to the frequency converter
are defined as Process Control Data (PCD).
Table 6.1
PCD 0 contains a 16-bit control word, where each bit
controls a specific function of the frequency converter, see
6.3 Control Profile. PCD 1 contains a 16-bit speed set point
in percentage format. See 6.2.3 Reference Handling.
The content of PCD 2 to PCD 9 is programmed in
12-21 Process Data Config Write and 12-22 Process Data
Config Read.
6.2.2 Process Status Data
Process data sent from the frequency converter contain
information about the current state of the frequency
converter.
PCD 9
write Table 6.2
PCD 0 contains a 16-bit status word, where each bit
contains information regarding a possible state of the
frequency converter.
PCD 9
PCD 1 contains per default the value of the current speed
read
of the frequency converter in percentage format (see 6.2.3
Reference Handling).
The content of PCD 2 to PCD 9 is programmed in
12-22 Process Data Config Read.
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Master slave
0 1 2
CTW MRV PCD
PCD write
Slave master
0 1 2 ......
STW MAV PCD ......
PCD read
6
...... 9
...... PCD
9
PCD
15
6