Modbus; Mb_Comm_Load - Siemens SIMATIC S7 System Manual

6.3.2

MODBUS

6.3.2.1

MB_COMM_LOAD

LAD
Parameter Parameter
type
PORT IN
BAUD IN
PARITY IN
FLOW_CTRL IN
RTS_ON_DLY IN
S7-1200 Programmable controller
System Manual, 11/2009, A5E02486680-02
FBD
Data type Description
UInt Communications port identifier:
After you install the CM module in the Device configuration, the port
identifier appears in the helper drop-list available at the PORT box
connection. This constant can also be referenced within the "Constants"
tab of the default 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

UInt RTS ON Delay Selection:
0 – (default) No delay from RTS active until the first character of the

message is transmitted
1 to 65535 – Delay in milliseconds from RTS active until the first

character of the message is transmitted (does not apply to RS-485
ports). RTS delays shall be applied independent of the FLOW_CTRL
selection.
Programming instructions
6.3 Global library instructions
The MB_COMM_LOAD instruction
configures a port on the Point-to-Point
(PtP) CM 1241 RS485 or CM 1241
RS232 module for Modbus RTU
protocol communications.
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