Modbus Error Messages - Endress+Hauser Proline Promass 84 MODBUS RS485 Operating Instructions Manual

Operation
42
INTEGER:
Selection 1st
1 – 0 – 3 – 2 * Byte 1
3 – 2 – 1 – 0 (MSB)
0 – 1 – 2 – 3 Byte 0
2 – 3 – 0 – 1 (LSB)
* = Factory setting
MSB = most significant byte
LSB = least significant byte
STRING:
Illustration using the example of a device parameter with a data length of 18 bytes.
Selection 1st
1 – 0 – 3 – 2 * Byte 1
3 – 2 – 1 – 0
0 – 1 – 2 – 3 Byte 0
2 – 3 – 0 – 1 (LSB)
* = Factory setting
MSB = most significant byte
LSB = least significant byte
5.5.6

MODBUS error messages

If the MODBUS slave detects an error in the request telegram from the master, it sends a reply to
the master in the form of an error message consisting of the slave address, function code, exception
code and check sum. To indicate that this is an error message, the lead bit of the returned function
code is used. The reason for the error is transmitted to the master by means of the exception code.
The following exception codes are supported by the measuring device:
Exception codes Description
01 ILLEGAL_FUNCTION
The function code sent by the master is not supported by the measuring device (slave).
!
Description of the function codes supported by the measuring device → ä 39.
02 ILLEGAL_DATA_ADDRESS
The register addressed by the master is not assigned (i.e. it does not exist) or the length of the
requested data is too big.
03 ILLEGAL_DATA_VALUE
• The master is attempting to write to a register which only allows read access.
• The value that appears in the data field is not permitted: e.g. range limits overshot or
incorrect data format.
04 SLAVE DEVICE FAILURE
The slave did not respond to the request telegram from the master or an error occurred when
processing the request telegram.
Sequence
2nd
Byte 0
(LSB)
Byte 1
(MSB)
Sequence
2nd ...
Byte 0 ...
(LSB)
Byte 1 ...
Note!
Proline Promass 84 MODBUS RS485
17th 18th
Byte 17 Byte 16
(MSB)
Byte 16 Byte 17
(MSB)
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