MLB-G1101 DTU User Guide
20
Rev 1.1
4 5.1
Longitudinal Redundancy Check or LRC
The LRC is used to ensure the data integrity of data exchanged between the interface
device.
The LRC character is appended to all data message exchange between the DTU and
Controller to detect and recover from transmission errors.
It is generated by using an 8-bits EXCLUSIVE-OR of all bytes between the STX and ETX
character (this would exclude the STX but include the ETX character).
Link Control Characters
The link control characters set are characters sets that are used by the messaging protocol
as shown in Table 8
Character
Hex
Decimal
Remarks
STX
02
02
Start of text framing character
ETX
03
03
End of text framing character
ACK
06
06
Affirmative acknowledgement
NAK
15
21
Negative acknowledgement
Table 8: link control characters set
Normal Request and Respond
Figure 5-3 shows the standard normal request/response transaction between the Controller
and DTU. The request message is of the standard message format
e.g. <STX><TransType><LEN><DATA><ETX><LRC>.
