Xylem H-3531 FlashLite - Manual (Page 74)

B-2 Modbus Protocol
H-3531
B.4 Holding Registers
There are 33 holding registers in the H-3531 FlashLite™, some are Read/Write registers and some
are Read Only registers. The user configurable settings are found in the Holding Registers. Table
2 below shows the contents on the Holding Registers followed by a description of each register.
Table 2 - Holding Registers
Info in Register Start Address # of 16-bit Registers Data Type
ID String 0 / “0000" 16 Char String
Modbus Address 17 / “0011" 1 Short Integer
Stage Units Select 18 / “0012" 1 Short Integer
***Reserved*** 19 / “0013" 1 Short Integer
Modbus Baudrate 20 / “0014" 1 Short Integer
Parity 21 / “0015" 1 Short Integer
User Stage Offset 22 / “0016" 2 32bit Float
User Stage Slope 24 / “0018” 2 32bit Float
Stage 26 / “001A” 2 32bit Float
Pressure 28 / “001C” 2 32bit Float
Temperature 30 / “001E” 2 32bit Float
Battery 32 / “0020” 2 32bit Float
B.4.0 ID String(RO)
The first registers in the Holding Registers are the ID string registers, this is the same ID
string that the SDI-12 ID command returns. Refer to SDI-12 ID command to see details of
the response. The ID string consists of 16, 16-bit registers. These registers can be read
separately but to get the full ID string the user must read all 16-registers at once. These
registers are RO (read only) registers. As shown in Table 2 the response to reading the ID
string is sent as a ASCII character string. Example, to read the full ID string the host must
send the request as follows: “aa0300000010crcc”
H-3531 FlashLite™ Response: “113 DAA H-3531001S#000000V011"
B.4.1 Modbus Address(R/W)
This holding register allows the user to change the Modbus address of the H-3531
FlashLite™. The programmable address range is: 1 - 247. The assigned Modbus address
factory default is: ‘1'. Address “0" is reserved for the broadcast address meaning that all
Modbus sensors will respond to address “0".