Example Configurations; Access One Serial Line From Multiple Tcp-Masters In A Network - VSCOM ModGate Plus User Manual

8 Example Configurations
8. Example Configurations
The ModGate Plus are intended to convert from Modbus on serial lines (RTU or ASCII) to Mod-
bus/TCP, and vice versa. This chapter will show some fairly often used installation variants. The
requirements of the application are given first, then the suggested configuration of ModGate Plus
with an explanation on why these parameters are selected. These configurations are for transport
and conversion of Modbus data, so configuration of IP Addresses is not covered here.
In general the ModGate Plus operate more similar to a Router than to a Gateway. The normal
configuration includes a list of Modbus IDs and the connections they are available with. These
connections are either serial or a TCP connection. In many applications those details are not
necessary, so more simple configurations are listed here.
To distinguish Master and Slave devices by its physical interfaces the devices using Modbus/TCP
will be prepended by TCP- while devices with a serial interface will carry the attribute serial.
Masters might be SCADA-Controllers, PCs with control software or other systems monitoring via
Modbus.

8.1. Access one serial line from multiple TCP-Masters in a Network

The serial line has one (RS232) or many (RS485) devices connected to it. There is no Modbus
master on the serial line. Instead different TCP-Masters on the network shall send requests to
specific devices, and the ModGate Plus shall enable this.
The configuratition is done as in section
Special Values to observe are
GatewayMode as LineMappingMode sends all requests from a TCP connection to the first serial
port. This is done without checking the Modbus ID in the request, so a configuration of IDs
for the serial port is not necessary.
Allow unknown clients assures the ModGate Plus accepts TCP connections from all stations,
without prior configuration of clients to accept connections.
This configuration is the default set of options for single port devices like the ModGate Plus 113.
Multi port devices need at least configuration of the GatewayMode as seen in figure 22.
June 2018
Modbus Gateway
ModGate Plus User Manual
Settings.
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