Hardy HI 6500 Series - Manual (Page 51)

Network Configuration 43
•
•
•
•
•
•
Modbus-RTU (over RS-485)
Step 1. Setup a slave address assigned to the HI 6500 series instrument from the
communications menu and the Modbus-RTU submenu.. Use a unique address
between 1 and 247
Step 2. Set the Baud Rate to the same as the master device, typically 9600 or 19,200
Step 3. Set the Parity Bit parameter to match that of the Modbus-RTU master (EVEN,
ODD, or OFF)
The RS 485 half duplex pinout is:
Modbus Setup
• Slave Address may be set to any number in the range of 1-247.
• Set Baud Rate parameter to match the settings of the Modbus master
• Set Parity to match the settings of the Modbus master
Modbus Functions
The Modbus functions allowed in the HI 6500 are: 
Function 3: Modbus Read Holding Registers 
Function 4: Modbus Read Input Registers 
Function 6: Modbus Write Single Register 
Function 16 (0x10): Modbus Write Multiple Registers.
Modbus Registers
This instrument has 64 16-bit MODBUS input registers and 64 16-bit output registers. The
data in these registers is in "big endian" format, meaning that the most significant byte
comes first.
• The first 6 registers (0 – 5) are used for the “command interface” in the unit.
• Registers 6 & 7 will contain the Net weight in 32 bit floating point format.
• Registers 8 & 9 will contain the Gross weight in 32 bit floating point format.
• Registers 10 and 11 will contain the statusword
• Registers 12 and 13 are for the count function.
Network Command Interface

The "network command interface" uses 6 registers (0 – 5) in and 6 registers out.
• Register 0: command (shown below)
• Register 1: status
• Registers 2, 3: Parameter number. See the diagnostics/parameters web page for a list of
parameter numbers.
GND DNC TR+ TR- PrtRX PrtTX
Signal
Ground DO Not
Connect TX+ & Rx- RX+ RS-232 
Pins not Printer
used