Alstom iSTAT M355, Руководство пользователя, Страница: 119 / 154

User Manual M3x5/EN M/B
iSTAT M3x5
Page 117
17. APPENDIX B2: MODBUS SUPPORTED FUNCTIONS AND USAGE
Code Code Function References
DEC HEX
3 03 to read from holding registers (4XXXX memory references)
4 04 to read from input registers (3XXXX memory references)
6 06 to write to a single holding register (4XXXX memory references)
16 10 to write to one or more holding registers (4XXXX memory references)
17 11 report slave ID 6 characters
77 4D read measurement string 1 byte value code (request)
82 52 re-read output buffer Use after broadcast request
17.1 03 read from holding registers
Reads the binary content of holding registers (4X references) in the slave. Broadcast is also
supported.
17.1.1 Request Frame
The query message specifies the starting register and quantity of registers (1 to 28) to be
read. Registers are addressed starting at zero.
Here is an example of a request to read registers 40009 ... 40010 from slave device 33:
Starting Register Register Count CRC
Slave Address Function Code HI LO HI LO LO HI
21 03 00 09 00 02
17.1.2 Response Frame
The register data in the response message is packed as two bytes per register, with the
binary contents right justified within each byte. For each register, the first byte contains the
high order bits and the second contains the low order bits.
Data is scanned in the slave at the rate of 28 registers per scan. The response is returned
when the data is completely assembled.
Here is an example of a response to the query:
Register Data CRC
Slave Address Function Code Byte Count HI LO HI LO LO HI
21 03 04 75 03 42 15
The contents of registers 40009 ... 40010 are 75 03 and 42 15 hex.
17.2 04 read from input registers
Reads the binary content of input registers (3X references) in the slave. Broadcast is also
supported
17.2.1 Request Frame
The query message specifies the starting register and quantity (1 to 28) of registers to be
read. Registers are addressed starting at zero.
Here is an example of a request to read registers 30036 ... 30037 from slave device 33:
Starting Register Register Count CRC
Slave Address Function Code HI LO HI LO LO HI