pamoja_modbus/
error.rs

1//! The error type for Modbus framing.
2
3/// What can go wrong building or reading a Modbus RTU frame.
4#[derive(Clone, Copy, Debug, PartialEq, Eq)]
5pub enum ModbusError {
6    /// A frame is shorter than the smallest valid RTU ADU (address, function, CRC).
7    FrameTooShort,
8    /// A frame or PDU is longer than the 256-byte RTU maximum allows.
9    FrameTooLong,
10    /// A received frame's CRC does not match its contents, so the frame is corrupt.
11    CrcMismatch {
12        /// The CRC computed over the frame's contents.
13        expected: u16,
14        /// The CRC the frame carried.
15        found: u16,
16    },
17    /// A write request named a number of values a single request cannot carry (it must
18    /// be between one and the function's maximum).
19    InvalidValueCount,
20    /// A response PDU is truncated or its declared byte count does not match its data.
21    MalformedResponse,
22}
23
24impl core::fmt::Display for ModbusError {
25    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
26        match self {
27            ModbusError::FrameTooShort => {
28                f.write_str("modbus frame is shorter than a valid RTU ADU")
29            }
30            ModbusError::FrameTooLong => {
31                f.write_str("modbus frame exceeds the 256-byte RTU maximum")
32            }
33            ModbusError::CrcMismatch { expected, found } => {
34                write!(
35                    f,
36                    "modbus CRC mismatch: expected {expected:#06x}, found {found:#06x}"
37                )
38            }
39            ModbusError::InvalidValueCount => {
40                f.write_str("modbus write request value count is out of range")
41            }
42            ModbusError::MalformedResponse => f.write_str("modbus response PDU is malformed"),
43        }
44    }
45}
46
47// `core::error::Error` rather than `std::error::Error`, so a caller on a
48// microcontroller gets the same trait a caller on a gateway does.
49impl core::error::Error for ModbusError {}
pamoja_modbus/error.rs

pamoja_modbus/
error.rs
