B5U027115E
GEN2 M30 UHF Serial-J1939 Manual – Rev. 1.15
Page 30 of
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4
Communication Features
The ‘master/slave’ protocol through the serial line (if available) expects that
the
BLUEBOX
(as ‘slave’) after the reception of a message send to him by the
‘host’ (as ‘master’), transmits a response message after a minimum time of
about 10 ms. By default, the
BLUEBOX
will apply
the following parameters:
address 255, baud rate 19200, 8 data bits, parity none and 1 stop bit. These
parameters can be modified as specified in the ‘Parameters Programming’
protocol command.
To simplify the explanations, the following conventions will be used:
SOH
Carattere 01h (0x01)
STX
Carattere 02h (0x02)
ETX
Carattere 03h (0x03)
EOT
Carattere 04h (0x04)
ENQ
Carattere 05h (0x05)
ACK
Carattere 06h (0x06)
NAK
Carattere 15h (0x15)
SYN
Carattere 16h (0x16)
CR
Carattere 0Dh (0x0D)
‘0’...’9’ Carattere 30h …39h (0x30 … 0x39)
‘A’…’F’ Carattere 41h …46h (0x41 … 0x46)
<..>
Carattere 30h …39h (0x30 … 0x39), 41h …46h (0x41 … 0x46)
<bcc> Checksum
This is the general structure of a message:
SOH <add h> <add l> … <bcc> CR
SOH
is the opening character,
CR
is the final character,
<bcc>
is the checking
character or checksum and it is calculated as 'xor' of the previous characters
starting from SOH and applying the following rule: if <bcc> = SOH or <bcc> =
CR or <bcc> = EOT , then <bcc> := <bcc>+1 (must be incremented of 1).