git.giacomolli.uk - onehouse/blob - doc/m31.rst

   1 ###############
   2  Ebyte M31 I/O
   3 ###############
   4
   5 The ``driver/m31`` package defines one host and up to fifteen expansion
   6 modules. A module's slice index is its slot. The host has eight digital
   7 inputs and eight digital outputs. Mixed expansions add eight of each,
   8 input expansions add sixteen inputs, output expansions add sixteen
   9 outputs, and analog expansions add eight voltage outputs.
  10
  11 Each point uses ``m{slot}.di{channel}``, ``m{slot}.do{channel}``, or
  12 ``m{slot}.ao{channel}``. Inputs, coils, and analog registers have
  13 independent zero-based address ranges that continue across modules.
  14 Analog registers represent zero through ten volts as zero through 10000.
  15 Hardware pulse widths are whole milliseconds from 50 through 65535.
  16 Their width registers start at ``0x30d4`` and their output-mode
  17 registers start at ``0x32c8``, both indexed by coil address. Mode zero
  18 is level control and mode one is pulse control.
  19
  20 Descriptors use manufacturer ``ebyte`` and firmware ``unknown``. The
  21 package does not read the host identity registers. Pulse capabilities
  22 accept commands but do not report transient coil state. Input
  23 capabilities are read-only.
  24
  25 Tests verify topology and descriptor values without a physical module.
  26 They do not confirm physical expansion limits or relay timing under
  27 load. The conservative sixteen-module limit includes the host.
  28
  29 ***************
  30  Modbus client
  31 ***************
  32
  33 ``NewTCPClient`` supplies a caller-owned, serialized connection through
  34 ``Client``. Connect selects the configured unit and has a two-second
  35 timeout. A request has a one-second write deadline and a two-second
  36 response deadline, both measured from its start. Caller deadlines and
  37 cancellation can stop it earlier. Each response must match the
  38 transaction, unit, function, length, and write acknowledgement.
  39 Supported functions are 01, 02, 03, 05, 15, and 16. No external Modbus
  40 package is required.
  41
  42 In-memory stream tests check request bytes, response validation,
  43 exceptions, truncation, cancellation, and timeouts. They do not verify a
  44 physical host or TCP network behavior.