RS485 and Modbus RTU Setting

RS485 will not respond in the setup screen.

Specs

Please see the page of the monitoring screen.

Cable wiring

Please see the page of mechanical and electrical installation.

Parameter setup

Please refer to the parameter set-up page.

Set-up steps as below:

1. Please set up the basic parameters first.

2. Connect cable according to the cable wiring instructions on this page.

3. This machine uses Modbus RTU protocol, communication parameter set-up as below:

   1. Set E04 for Modbus ID , and please make sure there is no other device using the same address.

   2. Set E05 for specifying communication Baud, this machine supports 9600, 19200, 38400 and 57600.

4. Please go back to the monitoring screen. RS485 only responses on monitoring screens.

5. If needed, please use F01 and F02 to set up the machine to do a communication test under simulation mode.

6. Please refer to the Modbus RTU protocol page for testing the memory with read and write instruction.

7. Turn off F02 simulation mode.

8. Finish.

Advanced parameter setting (available since FW 2.3.0)

E15 Byte format

This setting provides 4 options.

Option name	Full name
N.8.1	No parity bit with 1 stop bit
N.8.2	No parity bit with 2 stop bits
O.8.1	Odd parity bit with 1 stop bit.
E.8.1	Even parity bit with 1 stop bit

ST stands for start bit, D0 ~ D7 are data bits, SP stands for stop bit.

OP and EP stands for Odd-parity and Even-parity respectively

E16 Bit order

This option controls the direction of the transfer and selects LSB or MSB first.

LSB first is typically used for Modbus RTU.

The figure below presents the difference with N-8-1 mode.

E17 Endianness

This setting controls the byte order of multi-byte data. This setting solely interacts with the byte order of replied data. The byte format of register address and length in the commands still conform to the examples provided by manual. The figure below presents the byte order for when converting number 1000 in IEEE-754 format.

Example

The command below requests instantaneous flow speed (abbreviated to FS) and totalized flow rate ( abbreviated to TF) from the device.

The first line is the command sent by the master device. It is not affected by the current settings. Please refer to Modbus 04 command for details.

The second line is the response from the flow meter in Big Endian format. From left to right, 0x01 to 0x08 and CRC1 to CRC2 are not affected by the current settings. The order of the instantaneous flow rate (indicated as FS+number) and the accumulated flow rate (indicated as TF+number) in the response is also unaffected. Because it is set as Big Endian, the four bytes of the instantaneous flow rate (represented by FS3 to FS0) will be returned starting from FS3. The four bytes of the cumulative flow (represented by TF3 to TF0) will be returned starting from TF3.

The third line is the response from the flow meter in Little Endian format. From left to right, 0x01 to 0x08 and CRC1 to CRC2 are not affected by the current settings. The order of the instantaneous flow rate (indicated as FS+number) and the accumulated flow rate (indicated as TF+number) in the response is also unaffected. Because it is set as Little Endian, the four bytes of the instantaneous flow rate (represented by FS0 to FS3) will be returned starting from FS0. The four bytes of the cumulative flow (represented by TF0 to TF3) will be returned starting from TF0.