MULTI GAUGE CONTROLLER COMMUNICATION
Example: Write 2 words from address 0x0005.
Query:
TX: 01 10 00 05 00 02 04 22 33 44 55 3A D8
Response:
RX: 01 10 00 05 00 02 51 C9
6.4.6 RESPONSE IN CASE OF ERROR
The Modbus protocol deines the reaction if errors occurs. The Slave device is able to detect a
damaged query or a query which contains incorrect data. It responds then with error code.
However, transmission errors may occur to which Slave devices cannot respond. Then after waiting
the Master device will interpret the lack of response as a communication error. The Master should
then resend the query.
6.4.6.1 ERROR AND WARNING CODES
The Slave device, which detected a damaged query, or a query which contains incorrect data will
respond with an error message. An error message consists of the following elements.
Device address Function code Error code CRC
1 byte 1 byte 1 byte MSB LSB
The function code byte contains a transmitted function code, but with the most signiicant bit set
at 1 (it is the result of adding 128 to the function code - binary 10000000).
In response the error code indicates the type of the error detected.
The MG15 supports the type of the detected error:
Error
code
Error type Description
0x01 Incorrect
function
Function code is incorrect for Master (or slave) device.
0x02 Incorrect
address
Address out of range or start/end write/read in incorrect place of ta-
ble.
0x03 Incorrect
data /
argument
Data value of is inadmissible for the word addressed.
0x04 Device error Error occurred in the Master or Slave device when executing the op-
eration.
0x05 Acknowledge The Master (or Slave) device accepted the command and the opera-
tion is being executed. Its execution takes too long and the response
is sent back, to prevent the time limit error in the inquired device. The
Slave (or Master) may send a message in the next loop, to determine
whether the operation has been completed successfully.
continued on next page
User manual rev. 03 Page 97
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