Gas Turbine Flow Meter Rs485 Modbus Rtu Configuration
Silver Automation Instruments supply gas turbine flow meters, the gas turbine flow meter with varies functions according to customers' demands. Our turbine flow meters can have unscaled pulse output or scaled pulse output, 4-20mA or 0-20mA output, HART Protocol, RS 485 ,Mobus RTU communication. This article is talking about how to configure our SGW Gas turbine flow meter MODBUS RTU parameters.
SGW Series Gas turbine flow meter is MODBUS RTU.
The data format is n,8,1 ( 1 start bit,8 data bits, no check,1 stop bit.)
Gas meter Baud rate options: 1200, 2400,4800 , 9600,19200,default is 9600
The gas flow instrument address is “01-255”, “0”is for broadcasting.
Our protocol does not support broadcasting, others address is reserved.
The flow instruments applied MODBUS 0 x03 commands
The data in the protocol types:
Single floating-point number, format is IEEE754, the data is from high to low.
Double float-point r, format is IEEE754, the data is from high to low.
Unsigned int is 0-65535
Command 3 formats (read the register command)
Modbus Query
MODBUS Response
Error Response
Note: 01-Register address wrong, 02- Register length wrong, 03- CRC wrong
Gas turbine flow transmitterDate Definition
RS485,Modbus RTU Example (Flow meterinstrument address 01)
SGW Series Gas turbine flow meter is MODBUS RTU.
The data format is n,8,1 ( 1 start bit,8 data bits, no check,1 stop bit.)
Gas meter Baud rate options: 1200, 2400,4800 , 9600,19200,default is 9600
The gas flow instrument address is “01-255”, “0”is for broadcasting.
Our protocol does not support broadcasting, others address is reserved.
The flow instruments applied MODBUS 0 x03 commands
| Command 03(HEX) | Read single or multiple registers |
The data in the protocol types:
Single floating-point number, format is IEEE754, the data is from high to low.
Double float-point r, format is IEEE754, the data is from high to low.
Unsigned int is 0-65535
Command 3 formats (read the register command)
Modbus Query
| Address | 1 BYTE | 01-FF |
| Function | 1 BYTE | 3 |
| 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-FF |
| Function | 1 BYTE | 3 |
| Byte Count | 1 BYTE | N*2 |
| Input state | N*2 BYTE | |
| CRC Low | 1 BYTE | |
| CRC High | 1 BYTE |
| Address | 1 BYTE | 01-FF |
| Function | 1 BYTE | 83 |
| Error code | 1 BYTE | 01、02、03 (see note) |
| CRC Low | 1 BYTE | |
| CRC High | 1 BYTE |
Note: 01-Register address wrong, 02- Register length wrong, 03- CRC wrong
Gas turbine flow transmitterDate Definition
| Property | Address (hex) | Register length(word) | Datatype | Illustration |
| R | 1 | 2 | Float | Instant flow |
| R | 3 | 2 | Float | Totalized flow |
| R | 5 | 2 | Float | CPU voltage, unit V |
RS485,Modbus RTU Example (Flow meterinstrument 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 | Float high in the front, CRC low in the front |
| 00 00 00 00 (instant flow =0) | ||
| 42 84 00 00 (Totalized flow=66) | ||
| C1 86 |
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