Siemens S7-1200 System Manual page 533

Table 10- 12 Entering the data into the receive area
Protocol Entering the data i n the
variant receive area
TCP Ad hoc mode
TCP Data reception with
specified length
ISO on TCP Ad hoc mode
ISO on TCP protocol-controlled
Note
Ad hoc mode
The "ad hoc mode" exists with the TCP and ISO on TCP protocol variants. You set "ad hoc
mode" by assigning "65535" to the LEN parameter. The receive area is identical to the area
formed by DATA. The length of the received data will be output to the parameter
RCVD_LEN. Immediately after receiving a block of data, TRCV enters the data in the receive
area and sets NDR to 1.
If you store the data in an "optimized" DB (symbolic only), you can receive data only in
arrays of Byte, Char, USInt, and SInt data types.
Note
Importing of S7-300/400 STEP 7 projects containing "ad hoc mode" into the S7-1200
In S7-300/400 STEP 7 projects, "ad hoc mode" is selected by assigning "0" to the LEN
parameter. In the S7-1200, you set "ad hoc mode" by assigning "65535" to the LEN
parameter.
If you import an S7-300/400 STEP 7 project containing "ad hoc mode" into the S7-1200, you
must change the LEN parameter to "65535".
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
Parameter Value of the LEN parameter
" connection_type"
B#16#11 65535
B#16#11 0 (recommended) or 1 to
8192, except 65535
B#16#12 65535
B#16#12 0 (recommended) or 1 to
8192, except 65535
Communication
10.2 PROFINET
Value of the RCVD_LEN
parameter (bytes)
1 to 1472
1 to 8192
1 to 1472
1 to 8192
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