YOKOGAWA UT150L, User Manual

Page: 43 / 60

IM 05C01E22-10E
4-5
Chapter 4 MODBUS Communication
4.2.3 Function Codes
03 Reads data from multiple D registers.
●
Function
This function code reads the contents of successive D registers by the specified number of them
starting at a specified D register number.
• The maximum number of D registers to be read at a time is 32.
• For the format of responses in the event of failure, see subsection 4.2.4.
●
Message (for normal operation)
Element
Number of bytes in
RTU mode
Number of bytes in
ASCII mode
1
Number of
D Registers
(Upper Digit)
2
Start of
Message
Mark (:)
None
1
Number of
D Registers
(Lower Digit)
1
2
Error
Check
2
2
Address
Number (ADR)
1
2
None
End of Message
Mark
(CR + LF)
2
Function Code
(03)
1
2
D-Register Start
Number
(Upper Digit)
1
2 2
1
D-Register Start
Number
(Lower Digit)
Message (continued)
●
Response (for normal operation)
Element
Number of bytes in
RTU mode
Number of bytes in
ASCII mode
1
Contents of
D Registers
(Upper Digit)
2
Start of
Message
Mark (:)
None
1
Contents of
D Registers
(Lower Digit)
1
2
Error
Check
2
2
Address
Number
(ADR)
1
2
None
End of Message
Mark
(CR + LF)
2
Function
Code
(03)
1
2
Byte
Count
1
2
Contents of
D-Register
(Upper Digit)
1
2 2
1
Contents of
D-Register
(Lower Digit)
…
…
…
Response (continued)
●
Example: Reading the statuses of alarms 1 and 2 from the UT150L with address number 17.
The following message reads four successive D registers starting at alarm 1 (D0101) and address
number 17 in the ASCII mode.
[Message] [ : : ]11030064000286[CR][LF]
Start of message mark
“11”: address number 17, “03”: function code 03, “0064”: D register address 0101, “0002”: number
of D registers 2, and “86”: error check
* Numbers in quotation marks are hexadecimal.
The following response is returned with respect to the above message.
[Response] [ : : ]110304005A000A84[CR][LF]
Setting of alarm1, alarm2
“04”: byte count, “005A”: alarm 1 setpoint 90, “000A”: alarm 2 setting 10