Modbus; Communication Settings - Emerson Smart Wireless Gateway Reference Manual

Smart Wireless Gateway

MODBUS

Communication Settings

Figure 5-5. Modbus
Communications Page
5-4
The Gateway supports both Modbus RTU over the RS-485 serial port and
Modbus TCP over Ethernet. It functions as a sub device on the Modbus
network and must be polled by a Modbus master or client (host system).
It is import that the Modbus communication settings in the Gateway match the
setting in the Modbus master or client. Please refer to host system
documentation for more information on how to configure these settings. The
Modbus communication settings can be found by navigating to
Setup>Modbus>Communications.
One Modbus Address: When this option is selected, this address is used by
the Gateway for Modbus RTU communications.
Multiple Modbus Addresses: When this option is selected, a new column for
address will appear on the Modbus mapping page.
Modbus TCP Port: This is the TCP/IP port the Gateway uses for Modbus
TCP (Ethernet). To change TCP/IP port settings, see the Internal Firewall
section for more details.
Baud Rate: The data rate or speed of serial communications. This setting is
only required for Modbus RTU.
Parity: This setting determines parity (none, even, or odd) to use for error
checking purposes. This setting is only required for Modbus RTU.
Stop Bits: This setting determines the number (1 or 2) of stop bits to use
when ending a message. This setting is only required for Modbus RTU.
Response delay time (ms): This setting determines how long (ms) the
Gateway waits before responding to a Modbus request. This setting is only
required for Modbus RTU.
Unmapped register read response?: This is the value returned by the
Gateway if the Modbus master requests a register with no data assigned to it
(empty register). It is recommended this be set to zero fill to prevent errors.
Reference Manual
00809-0200-4420, Rev EA
November 2011