Parker Hannifin S.p.A. - Divisione S.B.C. “SPD” User’s Manual
79
[BK+LUN] = the LUN field (first 3 bits) indicates the number of bytes of the data transmitted
(a parameter or a PLC instruction); the values can range from 1 to 4. This value does not
include eventual 0 characters ($00) which are inserted after the values that coincide with the
character of transmission start ($7E). The length of every parameter is of 2 byte.
The BK field occupies the most significant 5 bit and represents the most significant 5 bit of
the parameter address.
[PAR] = write/read address of the PLC parameter or instruction.
The parameter address is the number of the parameter *2 su 13 bit: PAR represents the less
significant 8 bit of the address. The table used for the electronic cam is allocated from address
4096 on. The PLC INSTRUCTIONS occupy the area from address 0 to 255.
[D0]... [Dn] = data transmitted.
[CHK] = 256 module sum of all the fields excluding the [STX] (checksum).
13.2
Message types
[CMD1] = is the response message of the converter to a data request. The response message
has the following format:
[STX] [001+ADDR] [BK+LUN] [PAR] [D0]... [Dn] [CHK]
or it can be the confirmation message to a data write or data modify. In this case, the format
is the following:
[STX] [001+ADDR]
where ADDR always identifies which converter is answering.
[CMD2] = is the read message of an instruction in the PLC area. The message has the
following format:
[STX] [010+ADDR] [BK+LUN] [PAR] [CHK]
[CMD3] = is the write message to an instruction in the PLC area. The message has the
following format:
[STX] [011+ADDR] [BK+LUN] [PAR] [D0]... [Dn] [CHK]
[CMD4] = is the read message of a parameter. The message has the following format:
[STX] [100+ADDR] [BK+LUN] [PAR] [CHK]
[CMD5] = is the write message of a parameter. The message has the following format:
CMD
bit 7
bit 6
bit 5
type of message
1 0 0 1
converter
response
2 0 1 0
reading
a
pico-PLC
instruction
3 0 1 1
writing
a
pico-PLC
instruction
4 1 0 0
reading
a
parameter
5 1 0 1
writing
a
parameter
6 1 1 0
bit
modification
7
1
1
1
writing a parameter to all the
slaves
