Siemens SIMATIC S7 Manual page 18

connection_type
active_est
local_device_id
local_tsap_id_len
rem_subnet_id_
len
rem_staddr_len
rem_tsap_id_len
next_staddr_len
MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.1
The structure of the connection is defined here. It is used by the function
TCON when establishing the connection. The value depends on the PLC.
TCP (compatibility mode):
TCP:
The values vary depending on the used firmware. You can find further
information on the internet:
http://support.automation.siemens.com/WW/view/en/24294554
This parameter defines the way the connection is established (active or
passive). It is recommended that the Modbus client performs an active
connection establishment while the Modbus server establishes passive
connections.
Active connection establishment:
Passive connection establishment:
The local_device_id defines the IE interface of the used PN PLC. The
following values are necessary with the different PLC types.
IM 151-8 PN/DP CPU
CPU315 or 317
CPU319
CPU414 or CPU416
The length of the parameter local_tsap_id (= local port number) is defined
here.
Active connection establishment:
Passive connection establishment:
This parameter is currently not used. Please assign the value B#16#0.
The length of rem-staddr, i.e. the IP address of the communication partner, is
defined here. If an unspecified connection is to be used, no IP address is
required for the partner.
Unspecified connection:
Specified connection:
This parameter defines the length of rem_tsap_id, the port number of the
remote communication partner.
Active connection establishment:
Passive connection establishment:
This parameter defines the length of next_staddr as the distinction between
the communication running via an external CP or via the integrated PN
interface of the PLC.
PN interface of the PLC:
Parameterisation of the Modbus Communication
B#16#01 with CPU315 and 317 <= FW V2.3
B#16#11 with CPU315 and 317 >= FW V2.4,
IM 151-8 PN/DP CPU, CPU 319, CPU 414
and CPU416
TRUE
FALSE
B#16#1
B#16#2
B#16#3
B#16#5
0
2
B#16#0
B#16#4
2
0
B#16#0
4-4