Yokogawa PR300 Power and Energy Meter - Manual (Page 90)

<5. Modbus/RTU and ASCII Communication Protocols>
5-11
IM 77C01E01-10E
03 Reads data from multiple D registers
●
Function
This function code reads the contents of successive D registers by the specified number
starting with a specified D registers number.
• The maximum number of D registers to be read at a time is 64.
• For the format of responses in the event of failure, see subsection 5.1.4.
●
Message (for normal operation)
Element
Number of bytes
in RTU mode
Number of bytes
in ASCII mode
2
Error
Check
2
Start of
Message
Mark (:)
None
1
Station
Number
(ST-NO)
1
2
None
End of Message Mark
(CR + LF)
2
Function Code
(03)
1
2
D-Register
Start Number
2
4 4
2
Number of
D Registers
Message (continued)
●
Response (for normal operation)
Element
Number of bytes
in RTU mode
Number of bytes
in ASCII mode
Start of
Message
Mark (:)
None
1
Station
Number
(ST-NO)
1
2
2
Error
Check
2
None
End of Message Mark
(CR + LF)
2
Function
Code
(03)
1
2
Byte
Count
1
2
Contents of
D Register
2
4
4
2
Contents of
D Register
...
...
...
Response (continued)
●
Example (ASCII mode)
Read a series of four D registers starting with the D0201 (VT ratio and CT ratio) at station
number 11.
[Message] [:]0B0300C8000426[CR][LF]
“0B”:station number 11, “03”: function code 03, “00C8”: D register start number 201, “0004”:
number of D registers 4, and “26”: error check
* Numbers in quotation marks are hexadecimal.
The following response will be returned to the message above.
[Response]
[:]0B030800003F8000003F806C[CR][LF]
* The VT ratio and CT ratio data are floating point values. The combined value of D0201 and
D0202, 00003F80, represents 1. That of D0203 and D0204, which is also 00003F80,
represents 1 as well (the upper four digits, 3F80, and the lower four digits, 0000, are reversed).
* The floating point value of 3F800000 is the decimal equivalent of 1.