－20－
5.5.2 Read digital input data (read input relay status)
[Function code. 02 (02H)]
The specified number of "digital (ON/OFF) input data” are read out consecutively commencing with the
designated Reference No. For ON/OFF data, 8 Reference Nos. data are placed in one data (1 byte)
sequentially in number to constitute the response message data. The LSB (on DO side) of each data is a
digital data with the smallest number. If the number of Reference No. read is anything other than a multiple
of 8, an unnecessary bit becomes 0. An example of response message is the same as in "Function code
01", though its start number (Relative No.) is "Reference No. - 10001".
5.5.3 Read analog set value (read hold register contents)
[Function code. 03 (03H)]
The specified number of "analog parameters (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
Example) Reading range value (min/max/decimal point) of CH1 of the slave unit 2.
(Reading 3 Reference Nos. from 40104 to 40106 of analog parameters for the slave unit 2)
Reference No.
40104 40105 40106
Data
0
（
0000H
）
1000
（
03E8H
）
1
（
0001H
）
(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)
67H
Min. data (H)
00H
Number of Reference
No. (H)
00H
Min. data (L)
00H
Number of Reference
No. (L)
03H
Max. data (H)
03H
CRC (L)
B4H
Max. data (L)
E8H
CRC (H)
27H
DP data (H)
00H
DP data (L)
01H
CRC
(L)
74H
CRC (H)
35H
LRC
91H
LRC 09H
Note) Start No. (Relative No.) is given by "Reference No. - 40001". (Decimal number 103 (=40104-40001)
Hexadecimal 67H)
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 recorder) is
limited. (See Section 5.4).
5.5.4 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: 0.0 to 100.0
