Instruction manual

9
2
Reading (Address 1, Pattern 1, Step 1 step SV)
• Request message from the master
The number of the data indicates the data item to be read and it is fixed as (30H 30H 30H 31H).
(Fig. 6.2-4)
• A response message from the slave in normal status [When SV=600
(0258H)]
The number of response bytes indicates the number of bytes of the data which has been read, and
it is fixed as (30H 32H).
(Fig. 6.2-5)
• A response message from the slave in abnormal status (When non-existent data item is sent)
The function code MSB is set to 1 for the response message in abnormal status (83H).
If an abnormal code (02H: Non-existent data address) is returned, the error can be determined
by reading this code.
(Fig. 6.2-6)
3
Setting (Address 1, Pattern 1, Step 1 step SV)
When step SV is set to 600
(0258H)
• A request message from the master
(Fig. 6.2-7)
• A response message from the slave in normal status
(Fig. 6.2-8)
• A response message from the slave in abnormal status (When a value out of the setting range
is set.)
The function code MSB is set to 1 for the response message in abnormal status (86H).
If an abnormal code (03H: Value out of the setting range) is returned, the error can be determined
by reading this code.
(Fig. 6.2-9)
6.3 RTU mode
8-bit binary data in command is transmitted as it is.
Data format Start bit : 1 bit
Data bit : 8 bits
Parity : Even/No/Odd (Selectable)
Stop bit : 1 bit/2 bits (Selectable)
Error detection : CRC-16 (Cyclic Redundancy Check)
Data interval : 3.5 characters transmission time or less
Slave
address
Function
code
Data item
Error check
LRC
DelimiterHeader
(30H 31H)
Number of data
(3AH)
12 2 4
4
2
2
Number of
characters
(30H 33H)
(31H 31H 31H 30H)
(30H 30H 30H 31H)
(44H 41H)
(0DH 0AH)
Slave
address
Function
code
Number of
response bytes
Error check
LRC
DelimiterHeader
Data
12 2 2 4 2 2
(3AH)
(30H 31H)
(30H 33H)
(30H 32H)
(30H 32H 35H 38H)
(41H 30H)
(0DH 0AH)
Number of
characters
(0DH 0AH)
Slave
address
Function
code
Abnormal
code
Error check
LRC
DelimiterHeader
12 2 2 2 2
Number of
characters
(3AH)
(30H 31H) (38H 33H)
(30H 32H)
(37H 41H)
Slave
address
Function
code
Data item DelimiterHeader
(30H 31H)
Data
(3AH)
12 2 4 4 22
(30H 36H)
(31H 31H 31H 30H)
(30H 32H 35H 38H) (0DH 0AH)
Number of
characters
Error check
LRC
(37H 45H)
Slave
address
Function
code
Data item
Error check
LRC
DelimiterHeader
Data
12 2 4
42
2
Number of
characters
(3AH) (30H 31H) (30H 36H)
(31H 31H 31H 30H) (30H 32H 35H 38H) (37H 45H) (0DH 0AH)
Slave
address
Function
code
Abnormal
code
Error check
LRC
DelimiterHeader
2
Number of
characters
2
2221
(3AH) (30H 31H) (38H 36H) (30H 33H) (37H 36H) (0DH 0AH)