 | | | - Slave Address may be set to any number in the range of 1-247.
- Set Baud Rate and Parity to match the settings of the modbus master
- Termination maybe be set to Off, On, or Link. Link means that the termination is set on or off depending on whether pin 2 of the connector is low (on) or high (off). There is an internal pull up on pin 2 that will set the termination off if nothing is connected to it.
This instrument has 24 16 bit MODBUS input registers and 24 16 bit output registers. The data in these registers is in "big endian" format, meaning that the most significant byte comes first.
Network command interface
The PLC to Hi6501 "network command interface" uses 20 bytes (10 MODBUS registers) in and 20 bytes out.- Output
Bytes 0,1(MODBUS registers 0): command register
Bytes 2,3 (MODBUS register 1): aux command information register
Bytes 4,5,6,7 (MODBUS registers 2,3): parameter value
Bytes 8,9 (registers 4): Parameter number. See the diagnostics/parameters web page for a list of parameter numbers.
- Input
Bytes 0,1(MODBUS registers 0): command register
Bytes 2,3 (MODBUS register 1): Sample Counter and command status register
Bytes 4,5,6,7 (MODBUS registers 2,3): parameter value
Bytes 8,9 (registers 4): Parameter number. See the diagnostics/parameters web page for a list of parameter numbers.
Bytes 10,11 (registers 5): instrument status register
Bytes 12,13,14,15 (registers 6,7): net weight register
Bytes 16,17,18,19 (registers 8,9): gross weight register
The master sends a 'command' by writing a value the command register. Here is a list of command numbers:
- 0x00 : READPARAMCMD. To read a parameter, write 0 to the command register (register #0), and write the parameter number in the parameter number registers 4. The parameter value may then be read from registers 2 and 3. This value may be in integer or floating point format, depending on the parameter. The instrument status register in the reply will contain the system status word.
- Status word bit 0: A/D error.
- Status word bit 2(0x04): Motion status.
- Status word bit 7(0x80): Not Found - the requested parameter number does not exist.
- 0x01 : ZEROCMD. Write 1 to the command register to ZERO the gross weight. The status register will read 0 if this command succeeds. Error codes are 1 (A/D error), 3 (out of tolerance) and 4 (motion).
- 0x02 : TARECMD. Write 2 to the command register to Tare the net weight. The status register will read 0 if this command succeeds.Error codes are 1 (A/D error) and 4 (motion).
- 0x64 : CALLOWCMD. Perform the low step of a calibration.
- 0x65 : CALHIGHCMD. Perform the high step of a calibration.
- 0x66 : C2CALCMD. Do a C2 calibration.
- 0x92 : WRITEINTEGERCMD. Set the value of an integer parameter. Write the parameter number in the parameter number registers and the desired value in the parameter value registers.
- 0x93 : WRITEFLOATCMD. Set the value of a floating point parameter. Write the parameter number in the parameter number registers and the desired value in the parameter value registers.
- 0x96 : WRITENONVOLCMD. Write 0x96 to the command register to save parameters in non-volatile memory.
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