Reading acetylene value
|
Device address used in the following examples is 240 (0xF0). The values returned by the device differ depending on the measurement conditions. Your device may not return the same values. |
| Response | |
|---|---|
| Bytes on the line (hexadecimal) | Description |
| (silence for > 3.5 bytes) | Start of Modbus RTU frame |
| 0xF0 | OPT100 address |
| 0x03 | Function (Read Holding Registers) |
| 0x04 | Number of data bytes |
| 0x40 | Value of first register (least significant word) |
| 0x40 | |
| 0x00 | Value of second register (most significant word) |
| 0x00 | |
| 0x0E | Modbus RTU checksum |
| 0xE8 | |
| (silence for > 3.5 bytes) | End of Modbus RTU frame |
| Communication description | |
|---|---|
| Register number | 23 (1-based Modbus register number) = address 0x0016 (0-based address used in actual communication). |
| Data format | Two 16-bit Modbus registers interpreted as IEEE 754 binary32 floating point value, least significant word first. |
| Returned value | 0x40400000, which is binary32 representation of 3 (ppm). |