Dp Parameter Assignment Message; Structure Of The Dp Standard Section Of The - Siemens SIMATIC CP 541 Manual

DP Parameter Assignment Message

Introduction
Structure
DP Standard
Section
Communications Processor CP 541
EWA 4NEB 812 6188-02
The CP 541 needs the parameter assignment message in the DP start; it is
explained here. The DP master sends the DP parameter assignment message
to the DP slave (CP 541).
The parameter assignment message contains 7 bytes of data, byte 0 to byte 6.
It is structured according to DP Standard DIN E 19254, Part 3.
The structure of the 7 bytes according to the DP standard can be found in
Table D-1.
Table D-1 Structure of the DP Standard Section of the Parameter Assignment
Message
Byte Value
0 Station status
Watchdog factor
1 0 ... FF
H
These two bytes represent two factors for the response
monitoring time. monitoring time
2 0 ... FF
H
The response time is calculated with the following for-
mula: T
3 0 ... FF Response delay (min. T
H
This entry is not significant with the CP 541 because
parameter min. TSDR must be permanently entered via
DB1 as parameter SDT 1.
4, 5 001F Manufacturer identifier
H
The manufacturer identifier is a product-specific ID. The
CP 541 only accepts in the parameter assignment mes-
sage the manufacturer ID corresponding to the own ID.
If the ID in the parameter assignment message does not
agree with the own ID, an error message is issued.
6 Group identifier
Two or more DP slaves can be grouped with group iden-
tifier.
1
Meanings of the individual bits of the station status are given in Table D-2.
Meaning
1
10 ms factor 1
WD (byte 1)
)
SDR
D
factor 2
(byte 2)
D-1