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SLW Liquid Turbine Flowmeter RS485 Modbus Configuration

SLW Liquid turbine flow meter is a kind of cheap digital flow meter, it can have digital display to show instant flow and total flow , it can measure vegetable oil, ethanol, diesel, palm oil flow range.SLW series liquid turbine flow meter can have 4-20mA ,pulse output, scaled pulse output, Hart Protocol, Modbus Communication. This article is mainly talking about the configuration of RS485 Modbus Communications for SLW turbine flow meter.

 (RS485 MODBUS RTU CONFIGURATION)

This type of flow meter is MODBUS RTU.

The data format is n,8,1 ( 1 start bit,8 data bits, no check,1 stop bit.)

Baud rate options: 1200, 2400,4800 , 9600,19200

The instrument address is “01-99”, “0”is for broadcasting.

Our protocol does not support broadcasting, others address is reserved.

The flow measuring instruments applied MODBUS 0 x03 commands

Command 03(HEX)

Read single or multiple registers

THE data in the protocol is single floating-point number ,format is IEEE754, the data is from high to low.

Command 3 formats (read the register command)

Modbus Query

Address

1 BYTE

01-F7

Function

1 BYTE

03

Starting Address

2 BYTE

0-FFFF

Read Numbers

2 BYTE

N(1-7D)

CRC Low

1 BYTE

 

CRC High

1 BYTE

 

MODBUS Response

Address

1  BYTE

01-99

Function

1  BYTE

030610

Byte Count

1  BYTE

N*2

Input state

N*2  BYTE

 

CRC Low

1 BYTE

 

CRC High

1 BYTE

 

 Error Response

Address

1  BYTE

01-F7

Function

1  BYTE

83

Error code

1  BYTE

010203 (see note)

CRC Low

1 BYTE

 

CRC High

1 BYTE

 

Note: 01-Register address wrong, 02- Register length wrong, 03- CRC wrong

 

Date Definition

 

Property

Address (hex)

Register length(word)

Data type

Illustration

R

0001

2

Float

Instant flow

R

0003

2

Float

Totalized flow

R

0005

2

Float

CPU voltage, unit V

 

Example (turbine flow instrument address 01)

 

Query

01 03 0001 0004 15C9

CRC low in the front, and at the same time read instant flow and totalized flow.

Response

01 03 08

00 00 00 00 (instant flow =0)

42 84 00 00 (Totalized flow=66)

C1 86

Float high in the front, CRC low in the front

 

 welcome to contact Silver automation Instruments (www.silverinstruments.com )  to buy cheap turbine flow meter 

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