FCM 300 / FCD 300 / VLT
®
2800 / DP V1 PROFIBUS
■ FCM 300/FCD 300/VLT 2800 response time
The update time via the prodibus connection can be
divided in two parts: 1) The communication time, which
is the time it takes to trans mit data from the master to
the slave (FCM 300/FCD 300/VLT 2800 with profibus),
and 2) the internal update time, which is the time it
takes to transmit data between the FCM 300/FCD
300/VLT 2800 control c ard and the profibus.
Communication time (t
com
) depends on the actual
transmission speed (baudrate) and the type of master
in use. The minimum obtainable communication
time with the FCM 30 0/FCD 300/VLT 2800 w ith
PROFIBUS is approx. 100 msec per slave, when
using DP communication with 4 bytes of data (PPO
type 3) at 3 Mbaud. More data or lower transmission
speed will increase the communication time.
The internal update time (t
int
) depends on the type
of data in question as there are different channels for
the data transfer where time critic al data e.g. control
word has highest priority. The internal update time for
the different types of data are stated below.
Update time, t
int
Data FCD 300/ VLT 2800 FCM 300
Control word/Main reference (part of PPO) Max. 26 msec. Max. 65 msec.
Status word/Actual output frequency (part of PPO) Max. 26 msec. Max. 65 msec.
Parameter read (PCD 1-8) 40 msec. 40 msec.
Parameter write (PCD 1-2) 160 msec. 160 msec.
Parameter write (PCD 3-4) 320 msec. 320 msec.
Parameter write (PCD 5-8) 640 msec. 640 msec.
Parameter read (PCV) 41 msec. 41 msec.
Parameter write (PCV) 40 msec. 40 msec.
Acyclical data (single read, write) - 40 msec.
■ System update time
The system update time is the time it takes to
update all the s laves in the network when using
cyclical communication. The draw ing below
shows the value w hich is obtainable in theory
at 2 input and 2 output bytes.
MG.90.A5.02 - VLT is a registered Danfoss trademark
8
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