Detailed Description Of The Services; Variable Read, Multiple; Number Of Elements - Omron E5AN Communications Manual

5.4 Detailed Description of the Services

■ Variable Read, Multiple

Command Frame
Slave
address
1
Slave address
Function code
Read start address

Number of elements

CRC-16
To read from the variable area, set the required data in the command
frame, as shown in the following diagram.
Function Read
code start address
H'03
1 2
Name
Specify the E5CN/AN/EN/GN's unit number.
The unit number can be set between H'01 and H'63 hexadecimal (1
to 99 decimal).
The Read Variable Area function's function code is H'03.
Specify the address containing the data to be read.
See SECTION 6 Communications Data for Modbus for details on
addresses.
4-byte Mode
Specify 2 times the number of setting data items as the number of
elements to be read. The setting range for the number of elements is
H'0002 to H'006A (2 to 106).
When H'006A is set, 53 items of setting data can be read.
Example: When reading 2 items of setting data, set the number of
elements to H'0004.
2-byte Mode
Specify the number of setting data items to be read as the number of
elements.
The setting range for the number of elements is H'0001 to H'006A (1
to 106).
When H'006A is set, 106 items of setting data can be read.
Example: When reading two items of setting data, set the number of
elements to H'0002.
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.

5.4 Detailed Description of the Services

Number of
CRC-16
Elements
2
2 bytes
Description
5-9