Frequency Converter Response Time Behaviour; Time Behaviour During System Update - Danfoss VLT 5000 Operating Instructions Manual

Timing

Frequency converter response time behaviour

The period for the update through the PROFIBUS
connection can be subdivided into two portions:
1. The communication period, i.e. the time required
to transmit data from the master to the slave
(frequency converter with PROFIBUS option), and
2. the internal update period, i.e. the time required
to transmit data between the frequency converter
control card and the PROFIBUS option card.
The communication period (t
respective transmission speed (baud rate) and the
type of master being used. The shortest achievable
communication period is approximately 30 msec
per slave with the frequency converter PROFIBUS
option when DP communication with a data quantity
of 4 bytes (PPO type 3) at 12 Mbaud is used.
The communication period increases with more
data or lower transmission speeds.
The internal update period (t
respective data as there are different channels
for the transmission of data, with time-critical
data, such as the Control word, being given the
highest priority. The internal update time for the
respective data types is listed below.
Data
Control word/main reference
value (Part of PPO)
Status word/respective output
frequency (Part of PPO)
Parameter Read (PCD 1-8)
Parameter Write (PCD 1-2)
Parameter Write (PCD 3-4)
Parameter Write (PCD 5-8)
Parameter Read (PCV)
Parameter Write (PCV)
Acyclical data (read, write)

Time behaviour during system update

The system update period is the time required
to update all slaves of the network when cyclical
communication is used.
16
) depends on the
com
) depends on the
int
Update time,
int
t
2 msec.
2 msec.
2 msec.
40 msec.
80 msec.
160 msec.
20 msec.
20 msec.
20 msec.
VLT® 5000/ 5000 FLUX/ 6000 HVAC/
8000 AQUA PROFIBUS
The update time of a single slave is composed of both
the communication period (depending on the baud
rate) and the station delay (TSDR) in the slave, and of
the delay in the master associated with the station.
The station delay (TSDR) is the delay time from the
moment when a station receives the last bit of a
telegram to the moment when it sends the first bit
of the next telegram. The station delay is defined by
two parameters: the minimum station delay (TSDR
and the maximum station delay (TSDR
Current station delay for the PROFIBUS option:
- DP: 11 bit times
Current master station delay:
- This information must be provided by the
manufacturer of the respective PROFIBUS master.
Example
- DP master with 1.5 MBaud and PPO type
3 (4 byte data); the assumption here is for 50
bit times as master TSDR.
Time [msec] Action
0 Master starts data transmission
Last bit received in slave
Slave station delay
Slave starts data transmission
Last bit received in master
Master station delay
(50 bit times » 0.033)
Master ready for data transmission
to next slave
MG.90.G1.02 - VLT is a registered Danfoss trademark
)
min
).
max