3 MODBUS STANDARD FUNCTION DETAILS
3.15 Write File Record (FC: 15H) (SC: 06H)
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3.15 Write File Record (FC: 15H) (SC: 06H)
Operation description
Writes a value to one extended file register area or values to multiple extended file register areas.
Request message format (from master to slave)
N shown below is the total of the device data (n1 + ... + nm).
Specify the number of sub requests, m, and the total number of write points of each sub request, N (n1 + ... +
nm), so that the size of the protocol data unit of the request message does not exceed 253 bytes. The request
message will be discarded if the following condition is not met.
[Conditional formula] 253  2 + (m  7) + (N  2)
Response message format (from slave to master)
â– When completed successfully
The slave returns the request message received from the master as-is.
â– When completed with an error
• File number specification: The upper limit of the file numbers that can be received by an Ethernet-equipped module is the file register size of the mounted
CPU module.
(H) (L) (H) (L) (H) (L) (H) (L) (H) (L)
(H) (L) (H) (L) (H) (L) (H) (L) (H) (L)
15H
(06H)
(06H)
Number of
bytes
m×7+N×2
Data
File number
specification
Function code
Write start device
number
Sub-request 1
Reference
number
Number of write points
n1
Number of bytes m×7+N×2
Number of bytes m×7+N×2
Device data 1 Device data n1
Data
File number
specification
Write start device
number
Reference
number
Number of write points
nm
Device data 1 Device data nm
Sub-request m
(0001H to 007AH)(0000H to 270FH)(0000H to FFFFH)
(0000H to FFFFH) (0000H to 270FH) (0001H to 007AH)
95H
Data
Exception code
Function code
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