Omron E5CN-HT Communications Manual page 84

SECTION 4 Modbus Communications Procedure
Response Frame
Slave Function
address
1
Name
Slave address
Function code
Byte count
Number of elements
CRC-16
Response Code
Function
code
H'83
H'03
4-10
Read data (for the
Byte
number of elements)
code count
H'03
0 to 212 (2 × 106)
1 1
The value from the command frame is entered as-is.
This is the received function code.
When the function ended normally, the function code is left as-is. When an
error occurred, the hexadecimal value of H'80 is added to the function code
to indicate that the response is an error response.
Example: Received function code = H'03
Function code in response frame when an error occurred = H'83
Contains the number of bytes of read data.
Contains the number of setting data items that were read.
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
4.1 Data Format on page 5-3.
Error
Error name
code
H'02 Variable address error
H'03 Variable data error
--- Normal completion
◆ Reading Undisplayed Parameters
It is possible to read the parameters that are not displayed due to
display settings as well as the parameters that are never displayed in
the Controller.
Example Command and Response
The following example shows the command and response when
reading the process value (slave address: H'01).
Process Value in Four-byte Mode
• Address: H'0000; Read data: H'000003E8 (100.0 °C)
Command:
01
Response:
01 03
CRC-16
2
Description
The read start variable address is incorrect.
• The variable area number is incorrect.
The number of elements exceeds the
allowed range.
No errors were found.
03 00 00 00 02 C4 0B(CRC-16)
04 00 00 03 E8 FA 8D(CRC-16)
Cause