Echelon I/O Model Reference for Smart Transceivers and Neuron Chips - Manual (Page 77)

I/O Model Reference 67
Neuron Chip
Or
Smart Transceiver
Pass Token CMP_RESYNC Write Data
Pass Token
CMP_ACK
RESYNC
Write Data
Master Has
Token
Slave Has
Token
MASTER
SLAVE
Figure 24. Handshake Protocol Sequence between Master and Slave
When in possession of the write token, the device (Neuron Chip, Smart
Transceiver, or a host processor) can transfer up to 255 bytes of data. The stream
of data bytes is preceded by the command and length bytes. The token holder
keeps possession of the token until all data bytes have been written, after which
the token is passed to the attached device.
The same process can now be repeated by the other side or, alternatively, the
token can be passed back without any data.
Resynchronization Procedure
The procedure shown in Table 24 through Table 28 on page 70 applies to
master/slave A and master/slave B configuration. The master initiates the
resynchronization with a RESYNC (0x5A) command, and the slave acknowledges
with an ACKSYNC (0x07) command. If the slave does not respond, the master
continues to send the RESYNC command until the slave responds correctly.
Table 24. Resynchronization
Step Master Slave Comment
1 (Owns Token)
2 Write RESYNC Master initiates resynchronization
(0x5A)