−25−
6.5.3 Read analog set value (read hold register contents)
[Function code. 03 (03H)]
The specified number of “analog parameters (2 bytes: 16 bits)” is read out consecutively commencing
with the designated Reference No. The data is split into higher-order 8 bits and lower-order 8 bits
arranged sequentially in number to constitute a data of response message
Example) Reading P/I/D of the slave unit 2.
(Reading 3 Reference Nos. from 40206 to 40208 of analog parameters for the slave unit 2)
Reference No.
40206
40207
40208
Data
30
（
001EH
）
120
（
0078H
）
20
（
0014H
）
(RTU mode)
Master
→
Instruments Instruments
→
Master (normal)
Slave address
02H
Slave address
02H
Function code
03H
Function code
03H
Start No. (H)
00H
No. of data
06H
Start No. (L)
CDH
P data (H)
00H
Number of Reference No. (H)
00H
P data (L)
1EH
Number of Reference No. (L)
03H
I data (H)
00H
CRC (L)
94H
I data (L)
78H
CRC (H)
07H
D data (H)
00H
D data (L)
14H
CRC
(L)
1DH
CRC
(H)
91H
LRC 2BH
LRC
4DH
Note) Start No. (Relative No.) is given by “Reference No. - 40001”.
(Decimal number 205 (=40206–40001) Hexadecimal CDH)
Note) No. of data is the number of data bytes. (which is different from the requested number of data. In
the example given above, the requested number of reference No. is 3 and the number of data is
6).
Note) The number of data of a message receivable at one time (that can be transmitted from the
controller) is limited. (See Section 6.4).
6.5.4 Read analog input data (read input register contents)
[Function code. 04 (04H)]
The specified number of “analog input (2 bytes: 16 bits)” are read out consecutively commencing with
the designated Reference No. The data is split into higher-order 8 bits and lower-order 8 bits arranged
sequentially in number to constitute a data of response message. The response example is the same
as in “Function code 03”, though its start number (Relative No.) is “Reference No. – 30001”.
(Error check in ASCII mode)
Example: P=3.0%,I=120Sec,D=20Sec.
