Can a binary point ever drive a modulating actuator?

Only in a crude, non-modulating way — a binary output can drive a floating-point (tri-state) actuator by pulsing "open" and "close" contacts for timed durations, which approximates modulation through timing rather than a true analog signal. This is common on older or lower-cost DDC systems and is distinct from a true AO, which sends a continuous 0–10 VDC or 4–20 mA signal directly proportional to desired position.

What is a "multistate" or "multi-state value" point?

Many modern BACnet controllers support a Multistate Value/Input/Output object type — a point with a small fixed number of named states (e.g., 1=Off, 2=Low, 3=Medium, 4=High) that is neither purely binary (only 2 states) nor truly analog (infinite resolution). It is the correct object type for something like a 3-speed fan or an occupancy mode selector (Occupied/Unoccupied/Standby/Bypass).

Does BACnet define analog and binary points differently than LonWorks or proprietary DDC?

The underlying concept is universal, but the object model differs. BACnet defines standard object types Analog Input/Output/Value and Binary Input/Output/Value with standardized properties (Present_Value, Units, etc.), which is a major reason BACnet became the dominant open BAS protocol — any BACnet-compliant workstation can read any vendor's AI/BI objects without custom translation. LonWorks instead uses Standard Network Variable Types (SNVTs) that serve a similar purpose but with different naming and property structures. Proprietary DDC systems predate both and often use vendor-specific internal representations, which is exactly the interoperability problem BACnet and LonWorks were created to solve.

Why does the points list matter so much during design?

The points list (I/O schedule) is the master document that assigns every physical field device to a specific point type, controller, and I/O terminal before installation. Errors here — wiring a variable-position damper as binary, for instance — often aren't discovered until commissioning, when correcting them means re-terminating wiring, changing controller point configuration, and sometimes swapping the physical actuator, all far more expensive than catching the mismatch on paper during design review.

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Analog Points vs Binary Points in a BAS

Why "analog" doesn't mean a dial and "binary" doesn't mean a switch — the real distinction is how many possible values the point can report, and what a controller can do with the number it gets back.

Every point in a building automation system database is one of four kinds: analog input (AI), analog output (AO), binary input (BI), or binary output (BO). New BAS technicians often sort these by what the device physically looks like — a sensor feels "analog," a relay feels "binary" — but the actual test has nothing to do with the hardware's appearance. It's about the range of the signal the point carries. An analog point represents a continuously variable quantity across a range; a binary point represents one of exactly two discrete states. Confuse the two in a points list, a controller program, or a graphic, and you get a supply-air-temperature reading that can only ever say "hot" or "cold," or a damper command that tries to sit at 47% open on an output that physically can only be full-open or full-closed.