Mitsubishi Electric 800 Series Instruction Manual page 149

Normal response (Response message)
Slave address
H19
(8 bits)
 Read holding register access log (H46 or 70)
• Queries by function codes H03, H06, and H10 are supported. The number and start address of holding registers
successfully accessed by the previous communication are returned. "0" is returned for both the number and start address
for queries other than the function codes above.
• Query message
a. Slave address
H46
(8 bits)
(8 bits)
• Normal response (Response message)
a. Slave address
H46
(8 bits)
(8 bits)
• Query message setting
Message
a Slave address
b Function code
• Content of normal response
Message
c Starting address
d No. of points
 Example) Read the successful register start address and number of successful accesses from
slave address 25 (H19).
Query message
Slave address
H19 H46
(8 bits) (8 bits)
Normal response (Response message)
Slave address
H19 H10
(8 bits) (8 bits)
The number of holding registers that were successfully accessed was returned as two with the start address 41007 (Pr.7).
 Error response
• An error response is returned if the query message received from the master contains an illegal function, address or data.
No response is returned for parity, CRC, overrun, framing, and busy errors.
NOTE
• No response is also returned in the case of broadcast communication.
148
3. RS-485 Communication
3.5 MODBUS RTU
Function code Starting address
H10 H03
(8 bits) (8 bits)
b. Function
CRC check
code
L
(8 bits)
b. Function
c. Starting address
code
H
(8 bits)
Set the address to send messages to. Broadcast communication is not possible. (Invalid when "0"
is set.)
Set H46.
The start address of the holding register that was successfully accessed is returned.
Starting address = start register address (decimal) - 40001
For example, when starting address 0001 is returned, the holding register address that was
successfully accessed is 40002.
The number of holding registers that were successfully accessed is returned.
Function
CRC check
code
H8B
(8 bits)
Function
Starting address
code
H03
(8 bits)
Quantity of registers
HEE H00
(8 bits) (8 bits)
H
(8 bits)
d. No. of points
L H
(8 bits) (8 bits)
HD2
(8 bits)
No. of points
HEE H00
(8 bits) (8 bits)
H02 H22
(8 bits) (8 bits)
CRC check
L L
(8 bits) (8 bits)
Description
Description
CRC check
H02 H22
(8 bits) (8 bits)
CRC check
H61
(8 bits)
H
(8 bits)
H61
(8 bits)