Yokogawa PR300 Power and Energy Meter - Manual (Page 19)

2-10
<2. Setup>
IM 77C01E01-10E
2.2.3 Conditions for Ethernet-Serial Gateway Function
The Ethernet-serial gateway function is a function that reads/writes data from/to other
devices equipped with RS-485 serial communication function using the Modbus/TCP
protocol via the PR300.
With this function, the higher-level device can access the devices connected to the RS-485
serial communication line in the same way as to access the devices connected to Ethernet.
Ethernet
10BASE-T, 100BASE-TX
Station number 01 (fixed)
Higher-level device
PR300
(with Ethernet
communication function)
RS-485
Station number 02
(arbitrary)
Station number 03
(arbitrary)
Station number 04
(arbitrary)
(Example)
Device with RS-485 serial
communication function
Power Monitor of POWERCERT series
Digital indicating controller of
GREEN series
Signal conditioner of JUXTA series
The PR300 operates as a gateway that changes the Modbus/TCP protocol received via
network to the Modbus/RTU protocol for the serial devices connected to the RS-485
communication interface. Therefore, the devices supporting the Modbus/RTU protocol are
required for the devices to be connected.
NOTE
•
If the Ethernet-serial gateway function is used, set a station number other than 01 for
the RS-485 communication devices which are slaves of the PR300 connected to
Ethernet.
• If the Ethernet communication function is used, the RS-485 communication interface
is used specifically for the Ethernet-serial gateway function. Therefore, it is not pos-
sible for a higher-level device such as a PC to access the PR300 via the RS-485
communication interface.