Reading The Variable Area - Omron E5AR - MANUAL 2 User Manual

Section 7 Communication (Modbus)

7.5 Reading the variable area

The variable area is read by setting the required data in the following command frame.
Command
Response
7-10
Command frame
Slave Function Read start Number of
address mode address elements
H'03
1 1 2
Data name
Specify the "Unit No." of the E5AR/ER. Set in hexadeci-
Client address
mal from H'01 to H'63 (1 to 99).
Function code The function code for variable area read is H'03.
Specify the address of the setting data that you wish to
First address of read.
read For more information on addresses, see "Appendix Set-
ting list" (P.A-6).
Specify the number of setting data items that you wish to
read 2 for the number of elements. The setting range is
Number of
H'0002 to H'006A (2 to 106).
elements
Example: If the number of setting data sets is 2, specify
Check code calculated based on the value from the cli-
ent address to the data end. For the calculation method,
CRC-16
see "7.2 Frames ■ Command frame ● Example of
CRC-16 calculation" (P.7-4).
Response frame
Slave Function Byte Read data
address mode count Data 1
H'03 Most significant Least significant
1 1 1 Number of elements 2 bytes
Data n
Most significant Least significant
Data name
Client address The value from the command frame appears here.
This is the received function code.
In an error response frame, "H'80" is added to the
received function code to indicate that it is an error
Function code
response.
Example: Received function code = H'03
Byte count Number of bytes of data that were read.
Read data The setting data that was read.
This is a check code calculated from the client address
to the data end. For the calculation method, see "7.2
CRC-16
Frames ■ Command frame ● Example of CRC-16 cal-
culation" (P.7-4).
CRC-16
2 2 bytes
Explanation
H' 0004.
Data 1
Data n CRC-16
2
Explanation
Function code in error response frame = H'83