Struct AsyncClientCore 

pub struct AsyncClientCore { /* private fields */ }

Shared async client handle.

Owns the mpsc::Sender that drives the background async task and a watch::Receiver used for a synchronous has_pending_requests() query.

Dropping this value closes the channel, which causes the background ClientTask to exit cleanly via its cmd_rx.recv() returning None.

Implementations

impl AsyncClientCore

pub async fn connect(&self) -> Result<(), AsyncError>

Establishes the underlying transport connection.

Must be called once before issuing Modbus requests. Can be called again after a disconnect to reconnect.

pub fn has_pending_requests(&self) -> bool

Returns true when there are requests in-flight awaiting a response.

This is a synchronous check — no .await required.

pub fn set_request_timeout(&self, timeout: Duration)

Sets a per-request deadline applied to every subsequent request call.

If a response is not received within timeout, the method returns AsyncError::Timeout. The in-flight entry remains in the background task until the transport delivers or errors; calling connect resets transport state.

The timeout can be updated at any time and takes effect on the next request. Call clear_request_timeout to remove it.

pub fn clear_request_timeout(&self)

Removes the per-request timeout set by set_request_timeout, allowing requests to wait indefinitely for a server response.

pub async fn read_multiple_coils( &self, unit_id: u8, address: u16, quantity: u16, ) -> Result<Coils, AsyncError>

Reads multiple coils (FC 01) from address with the given quantity.

Returns the coil values packed into a Coils object.

pub async fn write_single_coil( &self, unit_id: u8, address: u16, value: bool, ) -> Result<(u16, bool), AsyncError>

Writes a single coil (FC 05) at address with the given boolean value.

Returns (address, value) echoed back by the server.

pub async fn write_multiple_coils( &self, unit_id: u8, address: u16, coils: &Coils, ) -> Result<(u16, u16), AsyncError>

Writes multiple coils (FC 15) starting at address.

Returns (starting_address, quantity) echoed back by the server.

pub async fn read_holding_registers( &self, unit_id: u8, address: u16, quantity: u16, ) -> Result<Registers, AsyncError>

Reads holding registers (FC 03) from address with the given quantity.

Returns the register values as a Registers object.

pub async fn read_input_registers( &self, unit_id: u8, address: u16, quantity: u16, ) -> Result<Registers, AsyncError>

Reads input registers (FC 04) from address with the given quantity.

Returns the register values as a Registers object.

pub async fn write_single_register( &self, unit_id: u8, address: u16, value: u16, ) -> Result<(u16, u16), AsyncError>

Writes a single holding register (FC 06) at address with value.

Returns (address, value) echoed back by the server.

pub async fn write_multiple_registers( &self, unit_id: u8, address: u16, values: &[u16], ) -> Result<(u16, u16), AsyncError>

Writes multiple holding registers (FC 16) starting at address.

Returns (starting_address, quantity) echoed back by the server.

pub async fn read_write_multiple_registers( &self, unit_id: u8, read_address: u16, read_quantity: u16, write_address: u16, write_values: &[u16], ) -> Result<Registers, AsyncError>

Performs a combined read/write on holding registers (FC 23).

Reads read_quantity registers starting at read_address and simultaneously writes write_values starting at write_address. Returns the read registers.

pub async fn mask_write_register( &self, unit_id: u8, address: u16, and_mask: u16, or_mask: u16, ) -> Result<(), AsyncError>

Applies an AND/OR bitmask to a holding register (FC 22).

The resulting register value is (current & and_mask) | (or_mask & !and_mask).

pub async fn read_discrete_inputs( &self, unit_id: u8, address: u16, quantity: u16, ) -> Result<DiscreteInputs, AsyncError>

Reads discrete inputs (FC 02) from address with the given quantity.

Returns the input states as a DiscreteInputs object.

pub async fn read_fifo_queue( &self, unit_id: u8, address: u16, ) -> Result<FifoQueue, AsyncError>

Reads the FIFO queue (FC 24) at address.

Returns up to 31 words from the FIFO queue as a FifoQueue object.

pub async fn read_file_record( &self, unit_id: u8, sub_request: &SubRequest, ) -> Result<Vec<SubRequestParams>, AsyncError>

Reads a file record (FC 20) described by sub_request.

Returns the sub-request response parameters for each requested record.

pub async fn write_file_record( &self, unit_id: u8, sub_request: &SubRequest, ) -> Result<(), AsyncError>

Writes a file record (FC 21) described by sub_request.

pub async fn read_device_identification( &self, unit_id: u8, read_device_id_code: ReadDeviceIdCode, object_id: ObjectId, ) -> Result<DeviceIdentificationResponse, AsyncError>

Reads device identification objects (FC 43 / MEI 14).

pub async fn encapsulated_interface_transport( &self, unit_id: u8, mei_type: EncapsulatedInterfaceType, data: &[u8], ) -> Result<(EncapsulatedInterfaceType, Vec<u8>), AsyncError>

Sends an encapsulated interface transport request (FC 43).

Returns the (mei_type, data) pair from the server response.

pub async fn read_exception_status(&self, unit_id: u8) -> Result<u8, AsyncError>

Reads the device exception status (FC 07).

pub async fn diagnostics( &self, unit_id: u8, sub_function: DiagnosticSubFunction, data: &[u16], ) -> Result<DiagnosticsDataResponse, AsyncError>

Sends a diagnostics request (FC 08).

Returns DiagnosticsDataResponse with echoed sub_function and data.

pub async fn get_comm_event_counter( &self, unit_id: u8, ) -> Result<(u16, u16), AsyncError>

Reads the communication event counter (FC 11).

Returns (status_word, event_count).

pub async fn get_comm_event_log( &self, unit_id: u8, ) -> Result<CommEventLogResponse, AsyncError>

Reads the communication event log (FC 12).

Returns (status, event_count, message_count, events).

pub async fn report_server_id(&self, unit_id: u8) -> Result<Vec<u8>, AsyncError>

Requests the server identifier data (FC 17).

Returns the raw server ID byte array.