Modbus Rtu Instructions - Siemens SIMATIC S7-1200 System Manual

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Communication processor and Modbus TCP

13.5 Modbus communication

Modbus RTU instructions

Modbus_Comm_Load (Configure SIPLUS I/O or port on the PtP module for Modbus RTU) instruction

Table 13- 70 Modbus_Comm_Load instruction

"Modbus_Comm_Load_DB"(

REQ:=_bool_in,

PORT:=_uint_in_,

BAUD:=_udint_in_,

PARITY:=_uint_in_,

FLOW_CTRL:=_uint_in_,

RTS_ON_DLY:=_uint_in_,

RTS_OFF_DLY:=_uint_in_,

RESP_TO:=_uint_in_,

DONE=>_bool_out,

ERROR=>_bool_out_,

STATUS=>_word_out_,

MB_DB:=_fbtref_inout_);

The Modbus_Comm_Load instruction configures

SIPLUS I/O or a PtP port for Modbus RTU pro-

tocol communications.

Modbus RTU port hardware options: Install up to

three CMs (RS485 or RS232), plus one CB

Modbus RTU SIPLUS I/O options: Install ET

200MP S7-1500CM PtP (RS485 / 422 or RS232)

or ET 200SP S7-1500 CM PtP (RS485 / 422 or

An instance data block is assigned automatically

when you place the Modbus_Comm_Load in-

struction in your program.

S7-1200 Programmable controller

System Manual, V4.2, 09/2016, A5E02486680-AK