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VIPA System 300S
n-Data (High, Low)
Example
Conversion
15
14
13
12
start_register-offset_DB_no. = 00h
Further values
start_register
hex
decimal
0000h
0
01FAh
500
0384h
900
03FFh
1023
HB130 | CP | 341-1CH01 | en | 18-40
Any value may be used as n-Data (High, Low).
Conversion Modbus addressing for FC 03, 06, 16
"Modbus address in the transmission message"
Param-start-address
from 0
For e.g. start_register = 80 (0050h) the conversion takes place with the following
approach:
start_register = 0050h
11
10
9
n
Data block DB = Base-DB-Number + start_register-offset_DB_no.
–
Data block DB = 800 + 0 = 800
n
Data word DBW = start_register-word-no. x 2
–
Data word DBW = 80 x 2 = 160
offset_DB_no.
word_no.
decimal
hex
0
000h
0
1F4h
1
184h
1
1FFh
8
7
6
5
start_register-word-no. = 50h
Base DB
number
decimal
decimal
0
800
500
800
388
800
511
800
Communication protocols
Modbus > Modbus Slave - Function codes
"SIMATIC memory area"
PLC-area
Data blocks commence at DB 800
4
3
2
DB
decimal
800
800
801
801
1
0
DBW
decimal
0
1000
776
1022
91
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