Enum Exception 

#[repr(u8)]
pub enum Exception {
    Undefined(u8),
    IllegalFunction = 1,
    IllegalDataAddress = 2,
    IllegalDataValue = 3,
    DeviceFailure = 4,
    Acknowledge = 5,
    DeviceBusy = 6,
    MemoryParityError = 8,
    GatewayPathUnavailable = 10,
    GatewayTargetDeviceFailedToRespond = 11,
}

Enumerates the Modbus application exceptions returned by a slave device, including a catch-all for codes not defined by the specification.

Variants

Undefined(u8)

Exception code not defined by this crate; preserves the raw value for diagnostics.

IllegalFunction = 1

Exception code 0x01: the function is not supported or the device state does not allow the requested operation (for example an unconfigured unit asked to return registers).

IllegalDataAddress = 2

Exception code 0x02: the combination of starting address and length extends beyond the valid data range implemented by the device.

IllegalDataValue = 3

Exception code 0x03: a value in the request payload is not acceptable to the device, or the payload structure is inconsistent (for example an incorrect implied length).

DeviceFailure = 4

Exception code 0x04: an unrecoverable fault occurred while the device attempted the requested action.

Acknowledge = 5

Exception code 0x05: the device accepted the request but needs a long interval to finish; the client should poll later (e.g., Poll Program Complete).

DeviceBusy = 6

Exception code 0x06: the device is busy processing a long-duration command and cannot handle the new request yet; the client should retry later.

MemoryParityError = 8

Exception code 0x08: while accessing extended file records (function codes 20/21, reference type 6) the device detected a memory parity error.

GatewayPathUnavailable = 10

Exception code 0x0A: a gateway could not allocate an internal path between the input and output ports, often due to misconfiguration or overload.

GatewayTargetDeviceFailedToRespond = 11

Exception code 0x0B: a gateway forwarded the request but received no response from the target device, which may be offline or unreachable.

Implementations

impl Exception

pub const fn as_code(&self) -> u8

Returns the Modbus exception code associated with this variant.

Examples

use modbus_rtu::Exception;

assert_eq!(Exception::Undefined(0x7F).as_code(), 0x7F);
assert_eq!(Exception::IllegalDataAddress.as_code(), 0x02);
assert_eq!(Exception::DeviceBusy.as_code(), 0x06);

pub fn from_code(code: u8) -> Self

Converts a Modbus exception code into its corresponding Exception variant. Undefined codes are wrapped in Exception::Undefined.

Examples

use modbus_rtu::Exception;

assert_eq!(Exception::from_code(0x05), Exception::Acknowledge);
assert_eq!(Exception::from_code(0xFF), Exception::Undefined(0xFF));

Trait Implementations

impl Clone for Exception

fn clone(&self) -> Exception

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Exception

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Exception

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Exception

fn eq(&self, other: &Exception) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Exception

impl Eq for Exception

impl StructuralPartialEq for Exception