LSIS S100 - Page 146

134
RS-485 Communication Features
• Transmission/reception buffer size: Transmission=39 bytes, Reception=44 bytes
• Monitor registration buffer: 8 Words
• SUM: Checks communication errors via sum.
SUM=a total of the lower 8 bits values for station ID, command and data (Station
ID+CMD+Data) in ASCII-HEX.
For example, a command to read 1 address from address 3000:
SUM=‘0’+‘1’+’R’+‘3’+‘0’+‘0’+‘0’+’1’ = 30h+31h+52h+33h+30h+30h+30h+31h = 1A7h (the
control value is not included: ENQ, ACK, NAK, etc.).
ENQ
Station ID
CMD
Address
Number of
Addresses
SUM
EOT
05h
‘01’
‘R’
‘3000’
‘1’
‘A7’
04h
1 byte
2 bytes
1 byte
4 bytes
1 byte
2 bytes
1 byte
Note
Broadcasting
Broadcasting sends commands to all inverters connected to the network simultaneously. When
commands are sent from station ID 255, each inverter acts on the command regardless of the station
ID. However no response is issued for commands transmitted by broadcasting.
5.3.1.1 Detailed Read Protocol
Read Request: Reads successive n words from address XXXX.
ENQ Station ID CMD Address
Number of
Addresses
SUM EOT
05h
‘01’-’FA’
‘R’
‘XXXX‘
‘1’-‘8’ = n
‘XX’
04h
1 byte
2 bytes
1 byte
4 bytes
1 byte
2 bytes
1 byte
Total bytes=12. Characters are displayed inside single quotation marks(‘).
Read Normal Response
ACK
Station ID
CMD
Data
SUM
EOT
06h
‘01’-‘FA’
‘R’
‘XXXX’
‘XX’
04h
1 byte
2 bytes
1 byte
n x 4 bytes
2 bytes
1 byte
Total bytes= (7 x n x 4): a maximum of 39