HART Multiplexer System KFD*-HM*-16
Diagnosis and fault elimination
DO
C
T-0
120D
06/
2014
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8.3.2
Structure of the first byte
If Bit 7 is set (1), the first status byte contains a summary of the communication
errors. This information is coded bit by bit.
If Bit 7 is cleared (0), the first status byte contains a summary of the command
responses. This information is numbered consecutively and not coded bit by bit.
Communication error
This Byte contains information concerning the reception of a message.
The individual bits indicate a detected error, which has resulted in non-acceptance of
the message. Thus neither can a response be given to the message. It is necessary
to repeat the command, to check the connections, to use the terminating resistors or
to reduce the baud rate.
Details can be found in /1/.
Command responses
The first byte contains information relating to the execution of a command. The
command-specific response code thus documents the execution of the command.
In contrast to the communication error, the command responses are not coded bit by
bit, but are numbered consecutively from 0 to 127.
Of the command responses signalled by the Multiplexer, two instances are warnings
(codes 8 and 31), in which the processing of the command is continued. In the other
cases, errors are indicated, that means that the initiating command could not be
correctly executed. Here, the remedy is given by the meaning of the code.
All the codes that occur on the HART system are described in /1/.
Bit
Meaning
7 6 5 4 3 2 1 0
1
Communication error, if Bit 7 = 1, coded bit by bit
1 1
Parity error
1
1
Overrun error
1
1
Message error
1
1
Checksum error
1
0
always 0 (reserved)
1
1
Input buffer overrun
1
1 (undefined)
Note
Note
