HART Multiplexer System KFD*-HM*-16
Operation
2018-04
73
7.3.2 Status/Response Code
Two status bytes, known as the Response code, are included in each field device message.
These include three types of information:
• Communication faults
• Command responses
• Device status
Dependent on bit 7, the first two types are contained in the first byte of the status.
The device status is always transferred in the second byte.
Structure of the First Byte (Communication Fault)
If bit 7 is set (1), the first status byte contains a summary of communication faults.
This information is coded bit by bit.
If bit 7 is deleted (0), the first status byte contains a summary of command responses.
This information is numbered and not coded bit by bit.
Communication Faults
The byte contains information concerning the receipt of a message. The individual bits indicate
a detected fault, which has resulted in the message not being accepted. It is therefore not
possible to provide a response to the message. This problem can only be avoided by:
• Repeating the command,
• Checking the connection,
• Using terminators, or
• Reducing the baud rate.
Bit Meaning
7 6 5 4 3 2 1 0
1 Communication fault, if bit 7 = 1, coded bit by bit
1 1 Parity fault
1 1 Overflow fault
1 1 Message fault
1 1 Checksum fault
1 0 Always 0 (reserved)
1 1 Receive buffer overflow
1 1 (Undefined)
Table 7.3
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