Mitsubishi Electric FR-F820-00077 Instruction Manual page 774

Ethernet communication (FR-F800-E)
Read holding register access log (H46 or 70)
● Queries by function codes H03 and H10 are supported.
The number and start address of holding registers successfully accessed by the previous commu-
nication are returned.
"0" is returned for both the number and start address for queries other than the function codes
above.
● Query message
³
Transaction
identifier
H
(8 bits)
● Normal response (Response message)
³
Transaction
identifier
H
(8 bits)
● Query message setting
Message
³ Transaction identifier
· Protocol Identifier
» Length field
¿ Unit identifier
´ Function
Tab. 5-317: Description of the query message
● Content of normal response
Message
² Starting address
¶ No. of points
Tab. 5-318: Description of normal response
5 - 602
·
Protocol Length field
Identifier
L H L
(8 bits) (8 bits) (8 bits) (8 bits)
·
Protocol Length field
Identifier
L H L
(8 bits) (8 bits) (8 bits) (8 bits)
Description
The master adds the data for the purpose of transaction control.
The same data is returned in the response from the slave.
Fixed to 0. (When the slave receives data other than 0, it does not send the response
message.)
0 is returned in the response from the slave.
The data length from the unit identifier to the data is stored in byte.
Fixed to 255
Set H46.
Description
The start address of the holding register that was successfully accessed is returned.
Starting address = start register address (decimal) – 40001
For example, when start 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.
» ¿
Unit identifier
H L
(8 bits)
(8 bits)
» ¿
Unit identifier
H L
(8 bits)
(8 bits)
´
Func-
tion
H46
(8 bits)
´ ²
Func- Starting
No. of points
tion address
H46 H L
(8 bits) (8 bits) (8 bits) (8 bits)
Parameters
¶
H L
(8 bits)