Discovery & capabilities¶

Before configuring a task you can enumerate what hardware is present and introspect what each subsystem can do. dtollib exposes two async discovery helpers plus a per-session capability query.

Design reference: design.md §20.

Enumerating boards¶

find_devices() returns one BoardInfo per installed DT-Open Layers board. It never raises — if the SDK is unavailable or no board is installed, you get an empty list and the failure is logged. (The dtol-diag CLI is the tool that distinguishes "SDK missing" from "no boards".)

import anyio
from dtollib import find_devices, find_subsystems


async def main() -> None:
    for board in await find_devices():
        print(board.name, board.model, board.driver_name, board.instance)
        for sub in await find_subsystems(board):
            print(f"  {sub.type.value} element={sub.element} "
                  f"channels={sub.num_channels}")


anyio.run(main)

find_subsystems(board) accepts a BoardInfo or a raw board-name string and returns the SubsystemInfo list for that board (also non-raising).

What the info models carry¶

BoardInfo: name (e.g. "DT9805(00)"), model, driver_name, instance.

SubsystemInfo exposes the most-used capability flags directly — type, element, num_channels, cgl_depth, and the booleans supports_singlevalue, supports_continuous, supports_simultaneous_sh, supports_multisensor, supports_dma, returns_floats, plus max_throughput_hz.

Capabilities of an open session¶

SubsystemInfo is the enumeration-time snapshot. For the full, richer CapabilitySet (built from olDaGetSSCaps + olDaGetSSCapsEx + olDaEnumSSCaps + olDaEnumChannelCaps), query an open session:

async with await open_device(spec) as session:
    caps = await session.capabilities()
    if not caps.supports_multisensor:
        print("This board can't do RTD / strain / bridge inputs.")
    if not caps.supports_continuous:
        print("D/A is single-value only — use session.write(), not play().")

This is the clean way to branch before configuring a feature the board may not have. The capability checks are also enforced at configure time: a spec that needs an absent capability raises DtolCapabilityError before any SDK call (see Channels and Counter/timer for the DT9805 / DT9806 specifics).

DT9805 / DT9806 capability reality¶

See plan-hardware-functional.md for the bench-verified detail behind this table.