5.4 Detailed Description of the Services
5-11
■ Write Variable Area
To write data to the variable area, set the required data in the command
frame, as shown in the following diagram.
Command Frame
Name Description
Slave address Specify the E5CN’s unit number.
The unit number can be set between H’01 and H’63 hexadecimal (1
to 99 decimal).
Function code The Write Variable Area function’s function code is H’10.
Write start address Specify the starting address where the setting data will be written.
See SECTION 6 Communications Data for Modbus for details on
addresses.
Number of elements Specify 2 times the number of setting data items as the number of
elements to be written.
The setting range for the number of elements is H’0002 to H’0010 (2
to 16).
Example: When writing 2 items of setting data, set the number of ele-
ments to H’0004.
Byte count Specify the number of bytes of write data.
CRC-16 This check code is calculated with the data from the slave address to
the end of the data.
For details on the CRC-16 calculation, see CRC-16 Calculation
Example in 5.1 Data Format on page 5-3.
11 2 2
2
1
H'10
CRC-16
Number of
Elements
Data 1 Data 1
Number of elements × 2 bytes
Slave
address
Function
code
Write
start address
Byte
count
Write data
Leftmost bytes Rightmost bytes
Leftmost bytes Rightmost bytes
Data n Data n
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