Legacy Modbus Rtu Instructions; Mb_Comm_Load (Configure Port On The Ptp Module For Modbus Rtu) - Siemens SIMATIC S7-1200 System Manual
Hide thumbs
Also See for SIMATIC S7-1200:
- Function manual (527 pages) ,
- Manual (364 pages) ,
- System manual (338 pages)
Table of Contents
Advertisement
Communication processor and Modbus TCP
13.9 Legacy Modbus RTU communication (CM/CB 1241 only)
13.9.3
Legacy Modbus RTU instructions
13.9.3.1
MB_COMM_LOAD (Configure port on the PtP module for Modbus RTU)
Table 13- 143 MB_COMM_LOAD instruction
LAD / FBD
Table 13- 144 Data types for the parameters
Parameter and type
REQ
IN
PORT
IN
BAUD
IN
PARITY
IN
FLOW_CTRL
IN
1
1270
SCL
"MB_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_);
Data type
Description
Bool
A low to high (positive edge) signal starts the operation.
(Version 2.0 only)
Port
After you install and configure a CM or CB communication device, the
port identifier appears in the parameter helper drop-list available at the
PORT box connection. The assigned CM or CB port value is the device
configuration property "hardware identifier". The port symbolic name is
assigned in the "System constants" tab of the PLC tag table.
UDInt
Baud rate selection:
300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 76800, 115200,
all other values are invalid
UInt
Parity selection:
0 – None
•
1 – Odd
•
2 – Even
•
UInt
Flow control selection:
0 – (default) no flow control
•
1 – Hardware flow control with RTS always ON (does not apply to
•
RS485 ports)
2 – Hardware flow control with RTS switched
•
Description
The MB_COMM_LOAD instruction configures a
PtP port for Modbus RTU protocol communica-
tions. Modbus port hardware options: Install up
to three CMs (RS485 or RS232), plus one CB
(R4845). An instance data block is assigned
automatically when you place the
MB_COMM_LOAD instruction in your program.
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
Advertisement
Table of Contents
