Module command 

Client command types for the async task channel.

This module defines the two enums used to communicate with the background tokio task that owns the transport:

• ClientRequest — the user-facing operation parameters, one variant per Modbus function code, carrying only the values the caller supplies. The task assigns the transaction id internally.
• TaskCommand — the full envelope sent over the mpsc channel, which wraps a ClientRequest together with the oneshot reply sender, or represents a connection request.

Shutdown is signalled implicitly by dropping the mpsc::Sender end of the channel; no explicit Shutdown variant is needed.

Enums

ClientRequest

User-supplied parameters for a single Modbus request.