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CHAPTER 5 - SERIAL INTERFACE
SeeLeveL ELD Link Format and Signal Format-RS-485
•
This documents the supported data exchange format between
the S
L
EE
EVE
Management unit.
•
Version 1.2, January 3, 2019. Initial Release, plus two revision.
•
The supported signal format is half duplex serial, RS485 voltage
levels, 9600 baud, 8 bit, no parity, 1 stop bit.
•
SeeLeveL hardware will act as a slave with an address of 0x19.
•
SeeLeveL hardware will have a 120 ohm termination resistor installed
but not bus bias resistors.
•
All messages
format: [Destination: SeeLeveL address = 0x19] [Originator: Master
address = 0x00] [total number of bytes in message]
[payload - optional depending on message]
bytes)]
•
All messages
format: [Destination: Master address = 0x00] [Originator: Garnet
address = 0x19] [total number of bytes in message]
[payload – optional depending on message]
bytes)]
•
All multi-byte parameters are transferred big-endian (MSB first)
•
Total number of bytes in message (1 byte)
•
Message ID (1 byte)
•
Payload (optional depending on the message)
•
Checksum (2 bytes) = direct sum of all preceding bytes, truncated
to 2 bytes
•
Allow for a 50ms timeout for replies (SeeLeveL Slave -> ELD Master)
•
The master must respond to handshake requests within 500ms.
•
There must be a minimum of 5ms dead-band (bus inactivity) between
messages on the bus. Any data between these dead-bands will be
considered as one message and will be parsed as such.
SeeLeveL Query Message
•
Value:
0x00
•
Allows the ELD to query the SeeLeveL device
•
[0x19][0x00][0x06][0x00][ 0x00][0x1F]
T-DP0301-B Manual
L Access ™ In Cab Display and a vehicle's ELD / Fleet
(ELD MASTER -> SeeLeveL
(SeeLeveL Slave -> ELD
(ELD Master-> SeeLeveL
Slave) obey the following
[Checksum (16 bit: 2
MASTER) obey the following
[Checksum (16 bit: 2
Slave)
[message
ID]
[message
ID]
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