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SeeLeveL Error Response
•
Value: 0x0F, 1 byte payload
•
SeeLeveL issues this response if a command/message is not supported.
Payload = unsupported message code.
•
Example: ELD has previously issued a SeeLeveL Query Alarm Liquid
Level Message (0x07) to a SeeLeveL device which does not support
alarms:
•
[0x00][0x19][0x07][0x0F][0x07][ 0x00][0x36]
SeeLeveL Liquid Level Report Message
•
Value: 0x10, 6 or 7 byte payload, depending on whether alarms are
supported
•
SeeLeveL Slave transmits liquid level (4 bytes = unsigned int32), number
of digits to the right of the decimal (1 byte), optical error status (1
byte), and alarm status (currently active = 0x01, not in alarm state =
0x00). The alarm status field is optional and is not transmitted by a
SeeLeveL device which does not support alarms. Optical error status:
no light = 0x00, low light level = 0x01, sunlight = 0x02, no error =
0x10. In the event that the optical error status is in an error condition,
the liquid level and the number of digits to the right of the decimal
is ignored.
•
For the liquid level, the first 4 bytes of the payload represent the hex
value of the level, not the BCD value.
•
Example: liquid level = 1,083.1, no optical error, alarms not supported.
•
[0x00][0x19][0x0C][0x10][0x00][0x00][0x2A][0x4F][0x01][0x10][ 0x00]
[0xBF]
•
ELD request needing handshake confirmation:
•
Send liquid level.
•
The handshake request is done every 25th time one of these requests
is received. The handshake must be responded to within 500ms, or
else the response is considered invalid. If no handshake is received,
is late, or is incorrect, then no response is sent. This helps prevent
"brute force" codebreaking attempts.
Handshake format:
•
Request from ELD is received by SeeLeveL
•
SeeLeveL responds with handshake request if more than 25 requests
have occurred since the last handshake. Otherwise, SeeLeveL sends
reply to ELD request.
Page 12
(SeeLeveL Slave -> ELD
(SeeLeveL Slave -> ELD Master)
NOTES
Master)
T-DP0301-B Manual
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