Struct CustomFunctionCode 

pub struct CustomFunctionCode {
    pub fc: u8,
    pub predict_request_length: Arc<dyn Fn(&[u8]) -> CustomFcPredict + Send + Sync + 'static>,
    pub predict_response_length: Arc<dyn Fn(&[u8]) -> CustomFcPredict + Send + Sync + 'static>,
    pub handle: Option<CustomFcHandler>,
}

Defines a non-standard / user-defined Modbus function code. Mirrors njs-modbus CustomFunctionCode.

Registration paths:

• crate::layers::application::RtuApplicationLayer::add_custom_function_code — framing only.
• crate::slave::ModbusSlave::add_custom_function_code — framing + slave-side dispatch.
• crate::master::ModbusMaster::add_custom_function_code + send_custom_fc — framing + request issuance.

The two predict_* callbacks declare how to derive the total RTU frame length (PDU + 2-byte CRC) from leading bytes; they are required so the framing FSM can advance without the deleted sliding-window CRC fallback.

Fields

fc: u8

Function code value (must fit in u8).

predict_request_length: Arc<dyn Fn(&[u8]) -> CustomFcPredict + Send + Sync + 'static>

Predict total RTU frame length for an incoming request (slave-side framing).

predict_response_length: Arc<dyn Fn(&[u8]) -> CustomFcPredict + Send + Sync + 'static>

Predict total RTU frame length for an incoming response (master-side framing).

handle: Option<CustomFcHandler>

Slave-side handler. Returning Err is turned into a Modbus exception response by the slave. If handle is None, the slave returns an ILLEGAL_FUNCTION exception for this FC.

Trait Implementations

impl Clone for CustomFunctionCode

fn clone(&self) -> CustomFunctionCode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CustomFunctionCode

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

Formats the value using the given formatter.