sylvac PLC Mode D'emploi page 74

B.2 Frame description
Command frame format
Address field (3..5 bytes)
Where :
Address field : The slave number (1...247, 0=reserved for broadcast)
Format : #NNN# (NNN=1..3 ascii digits)
Note : if address field is fully omitted, the slave assumes it is the only one on the bus. If its own address is 0, it also answers without any
address field, allowing a dialog compatible with Proximity commands, but on the RS485 bus. An answer is send on the bus in response to a
bus request (not from keyboard, digital inputs or proximity).
Command field : Same as RS232-Proximity commands (see chapter 11)
End of Frame :
Answer format
Address field (3..5 bytes)
Command field (any number of bytes)
Ascii CR (0x0D) or CRLF (0x0D, 0X0A)
Response field (any number of bytes)
End of Frame (1 byte)
End of Frame (1 byte)