Exchanging data using the SIMATIC FB’s
ASCII | 3964R | RK512
18
Parameters for data transfer for SIMATIC S7
The control data or user data to be exchanged is copied to a special PLC memory area
– the data block (DB) – from where the PLC writes the data to the SPI 3 through the DP
master. User data always starts at DW0.
The following parameters must be specified when calling the FB’s. The tables indicate
which of the parameters are required for each of the FB’s:
Parameters for address information:
specify the location and length of the address array in the PLC address space .
Parameters for user data:
specify the location of the send/receive data blocks used for exchanging telegrams .
Start of user data
DW0
User data
Length
DWX
End of user data
Name
Type
Description / function
present in:
FB100
FB101
FB103
A_Anfang
POINTER
Starting address of send data area
(z. B.: M2.0, A5.0, DB10.DBX8.0)
X
X
X
E_Anfang
POINTER
Starting address of receive data area
(z. B.: M2.0, E5.0, DB10.DBX8.0)
X
X
X
EA_Laenge INTEGER
Length of I/O area of the SPI 3 (in bytes)
X
X
X
Name
Type
Description / function
present in:
FB100
FB101
FB103
DB_Data
Block_DB
Data block for sending/receiving telegrams
(e.g.: DB37, DB38)
X
X
Laenge
WORD
Length of data to send/receive (in bytes)
(e.g.: Send: MB40, B#16#0A / Receive:
MB40, DB3.DBB5)
X
X
