Structure Of The Data Telegram For Tcp/Ip Or Dust1 Connection - Siemens SIMATIC FM 458-1 DP User Manual

4.7.3.4

Structure of the data telegram for TCP/IP or DUST1 connection

HINWEIS
Application Module FM 458-1 DP - User Manual
A5E01078222-02 Edition 03.2009
If the communications link involves a TCP/IP or DUST1 coupling, then
the data telegram structure must be carefully observed. This is described
in the following. The data telegrams are "generated" using the function
blocks CTV and CRV.
The data telegram is defined so that all of the tabular values can be
transferred in a data block as well as in several data blocks.
The structure of a data block is shown in the following table:
Data type Description
char [4] Telegram ID
Each table telegram is identified with the "TAB0" ID
u_int16 Telegram commands (bit-coded)
1: New table (rising edge, from 0 -> 1)
2: End of table
u_int16 Data format (REAL=1, DINT=2)
u_int32 No. of the actual data block
u_int32 No. of tabular values (X and Y values)
The number of values must always be an even number. This
means that always the same number of X and Y values are
transferred.
u_int32 [56] / Array with tabular values. (X and Y values, always alternating)
float [56]
The TAB or the TAB_D sends an acknowledgement to the sender for
each data block received.
The structure of the acknowledge telegram is shown in the following
table:
Data type Description
char [4] Telegram ID
Identifies each table telegram with the "TAB0" ID
u_int32 No. of the actual data block
u_int32 Status / error numbers
0xB210 OK (data block is o.k.) ......
New table data is now transferred into the inactive table if the "New
table" command is set.
After the "End of table" command has been received, all additional
table data are rejected until the "New table" command is received.
Configuring
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