700-SDI-RADAR-300WL-Man Rev 2 11 Apr Mar 2022
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Part# 21371
ASPEED:
The speed readout of averaged speed in currently selected units, formatted
same as current speed.
CDIR:
-1 for outgoing, and 1 for incoming flow.
LVLTEMP
: Temperature on level senor device, in degrees Celsius.
ANGLE:
The measured tilt angle, in degrees, 0 being horizontal.
LEVEL:
The measured tilt angle, in meters.
DISCH:
The measured discharge, in m3/s.
CSUM:
Checksum, calculated by adding in modulo 256 the two byte values of the all byte
values first byte.
4.2.4
MODBUS PROTOCOL (RS-485)
When configured in Modbus operation mode, the unit responds to Modbus requests over the
RS-485 data line. The baud rate is configured through the PC application, and 1 stop bit, even parity,
8 dana bits configuration is used.
Modbus registers that are accessed by Modbus protocol are 16-bit (2-byte) registers. Any number of
registers can be read or written over Modbus.
Modbus is a request-response protocol where a master (such as datalogger) sends out requests and
slave devices (such as the 300 WL) respond. The request and response format, with example, is
given in tables 4-1 through 4-4. In each request, the master can either ask the slave to retrieve the
value of one or more registers, or the master can set the value of one or more registers. Each
register holds one 16-bit value.
Table 4-1: Master Request Format
Name
Addr
Fun
Data start Addr
Data#of regs
CRC16
Length
1 byte
1 byte
2 bytes (H.L.)
2 bytes (H.L.)
2 bytes (L.H.)
Example
0X01
0X03
0X00
0X00
0X00
0X01
0X84
0X0A
Table 4-2: Request Example
Name
Content
Detail
Address
0X01
Slave address (Sensor id)
Function
0X03
Read slave info
Data start Addr
0X00
The address of the first register to read (HIGH)
0X00
The address of the first register to read (LOW) – Sensor ID
reg
Data of regs
0X00
High
0X01
Low (read only 1 register)
CRC16
0X84
CRC Low
0X0A
CRC High