NORD Drivesystems BU0020 - Manual (Page 70)

PROFIBUS DP – Supplementary manual options for NORD - Frequency Inverters
70 BU 0020 GB-2612
7. Data transmission
Pos: 120 /Anleitungen/Bussysteme/6. Datenübertragung/Profibus [BU0020]Struktur der Nutzdaten @ 1\mod_1336380175752_388.docx @ 25276 @ 2 @ 1
7.1 Structure of reference data
This section describes the cyclic data traffic between the master and the frequency inverter.
The reference data is divided into two sections:
• PKW section (Parameterisation; Parameter Identification- Value)
• PZD section (Processdata)
Parameter values can be read and written via the PKW section of the reference data. All tasks which
are carried out via the PKW interface are essentially tasks for configuration, monitoring or diagnosis.
The PZD section serves to control the frequency inverter. The control word or status word as well as
the setpoint and actual values are transferred in the process data.
Access always consists of an order and a response telegram. In the order telegram, the reference
data is transferred to the slave. In the response telegram, the reference data is transferred from the
slave to the master. The structure of both telegrams is identical.
MASTER SLAVE
Parameter order Control word + Setpoint
Parameter response Status word + Actual
value
PKW section PZD section
Order telegram
Response telegram
Processing
Fig. 10: Telegram traffic / structure of reference data area
Processing of the process data is carried out immediately in the FI (high priority), in order to ensure a
rapid reaction to control commands or a change in status can be transmitted to the master without
delay.
On the other hand, the processing speed of the PKW data has a lower priority, so that processing may
take considerably longer.
Pos: 121 /Anleitungen/Bussysteme/6. Datenübertragung/Profibus [BU0020]PPO- Typen @ 1\mod_1336380543649_388.docx @ 25300 @ 25 @ 1