Yokogawa PR300 Power and Energy Meter - Manual (Page 63)

A-6 IM 77C01E01-01E
Appendix 1 Specifications of PR300
Modbus/TCP function
Code
03
06
08
16
Function
Reads data from multiple D registers
Writes data into D register
Performs loopback test
Writes data into multiple D registers
Description
Capable of reading data from up to 64 registers continuously.
Capable of writing data into one resiter.
Capable of performing a communication test.
Capable of writing data into up to 32 registers continuously.
Overview of Modbus/TCP protocol
PDU
The Simple Protocol Data Unit (PDU) is the same as
Modbus/RTU (Modbus protocol via serial communication).
MBAP Header Function code Data
The structure of the Modbus/TCP protocol is as follows:
Byte No
Description
0
Transaction ID
1 2
Protocol ID
3 4
Number of bytes
5 6
Unit ID
The Modbus Application Protocol Header (MBAP Header) is made of the
following seven bytes:
Ethernet - Serial gateway function
Equipped with an Ethernet communication connector and an RS-485 communication terminal, the
PR300 receives a Modbus/TCP command from Ethernet and relays it to the RS-485 communication
terminal. The PR300 allows connection to RS-485 serial communication devices (Modbus/RTU
protocol) via the network.
Higher-level device
IP address [192.168.1.1]
(arbitrary)
Ethernet
10BASE-T/100BASE-TX
Station number 01 (fixed)
IP address [192.168.1.2] (arbitrary)
PR300 (with Ethernet
communication function)
RS-485 connection
Station number 02
(arbitrary) Station number 10
(arbitrary)
RS-485 serial communication device
Power monitor of POWERCERT Series
Digital indicating controller of GREEN Series
Signal conditioner of JUXTA Series
(Example)
RS-485 communication
Protocol
Baud rate
Parity
Stop bit
Data length
Modbus/RTU
9600bps
None, even, odd
1 bit
8 bits
(Note) If Ethernet communication is used, the RS-485 communication interface is
used specifically for the Ethernet-serial gateway function. Therefore, it is not
possible for a higher-level device such as a PC to access the PR300 via the
RS-485 communication interface.
Standard Performance
Accuracy rating Active energy/optional active energy (Wh) Ϯ0.5% (EN60687 accuracy: Class 0.5 or equivalent)
Active power (W) Ϯ0.5% of F.S.
Voltage (V) Ϯ0.25% of F.S. (voltage rms)
Current (A) Ϯ0.25% of F.S. (current rms)
Frequency (Hz) Ϯ0.5Hz
Demand Ϯ0.5%
Calculation accuracy The value is calculated to Ϯ1 digit from the measured value for reactive energy, apparent
energy, reactive power, apparent power, power factor, or current.*
* Current is only for the 2.5-element measurement.
Backup upon power failure
The last integrated values obtained immediately before the power failure are held for active
energy, regenerative energy, reactive energy, and apparent energy.