Ad Hoc Mode - Siemens S7-1200 System Manual

Communication
10.2 PROFINET
Table 10- 1 Protocols and communication instructions for each
Protocol Usage examples
TCP CPU-to-CPU
communication
Transport of frames
ISO on TCP CPU-to-CPU
communication
Message
fragmentation and re-
assembly
UDP CPU-to-CPU
communication
User program
communications
S7 communication CPU-to-CPU
communication
Read/write data
from/to a CPU
PROFINET RT CPU-to-PROFINET
IO device
communication
10.2.2.3

Ad hoc mode

Typically, TCP and ISO-on-TCP receive data packets of a specified length, ranging from 1 to
8192 bytes. However, the TRCV_C and TRCV communication instructions also provide an
"ad hoc" communications mode that can receive data packets of a variable length from 1 to
1472 bytes.
Note
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.
To configure the TRCV_C or TRCV instruction for ad hoc mode, set the ADHOC instruction
input parameter.
If you do not call the TRCV_C or TRCV instruction in ad hoc mode frequently, you could
receive more than one packet in one call. For example: If you were to receive five 100-byte
packets with one call, TCP would deliver these five packets as one 500-byte packet, while
ISO-on-TCP would restructure the packets into five 100-byte packets.
518
Entering data in the
receive area
Ad hoc mode
Data reception with
specified length
Ad hoc mode
Protocol-controlled
User Datagram Protocol
Data transmission and
reception with specified
length
Data transmission and
reception with specified
length
Communication
instructions
Only TRCV_C and
TRCV
TSEND_C, TRCV_C,
TCON, TDISCON,
TSEND, and TRCV
Only TRCV_C and
TRCV
TSEND_C, TRCV_C,
TCON, TDISCON,
TSEND, and TRCV
TUSEND and TURCV
GET and PUT
Built-in
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
Addressing type
Assigns port numbers to
the Local (active) and
Partner (passive)
devices
Assigns TSAPs to the
Local (active) and
Partner (passive)
devices
Assigns port numbers to
the Local (active) and
Partner (passive)
devices, but is not a
dedicated connection
Assigns TSAPs to the
Local (active) and
Partner (passive)
devices
Built-in