Serial Remotes With Two Serial Ports - GE MDS SD Series Technical Manual

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In this example, the Host Computer is connected directly to the radio's
Ethernet port, and the RTUs at the Remote sites are connected to the
transceiver via the radio's
ture, used at the master, efficiently passes TCP payload over the air, and
eliminates the need for an external terminal server. (
used for payload data if properly configured via the management
system. See next example.)
Ethernet Data Port Menu
HOST COMPUTER
(TCP Server)
REMOTE RADIO
(One of several possible sites)
To COM2
Serial Port
MODBUS® SERIAL RTU
Figure 9. IP Polling of Serial Remotes

Serial Remotes with Two Serial Ports

In some cases, it is necessary to poll more than one RTU at a Remote
site. Figure 10 shows an example of this type of system. Here, two
RTUs are connected to each Remote transceiver, by using both of the
radio's serial ports—
COM1
By default, the radio's
COM1
functions with a connected PC, but it may be configured for data service
using the management system. This arrangement allows two telemetry
networks to share a single radio system.
In such a system, each RTU gets every message from the host computer,
and the underlying protocol (e.g., Modbus, DNP, etc.) sorts out which
messages are applicable to a specific RTU.
SD Series Technical Manual
serial data ports. The IP Payload fea-
COM2
Invisible place holder
MASTER RADIO
(TCP Client)
To Ethernet Port
MODBUS RTU
Protocol
REMOTE RADIO
(One of several possible sites)
MODBUS® SERIAL RTU
and .
COM2
port is configured for serial management
MDS 05-4846A01, Rev. D
may also be
COM1
To COM2
Serial Port