node-red-contrib-knx-ultimate/KNXEngine/dptlib/dpt3.js

Control your KNX intallation via Node-Red! Single Node KNX IN/OUT with optional ETS group address importer. Easy to use and highly configurable.

/**
* KNXEngine - a KNX protocol stack in Javascript
* (C) 2020-2022 Supergiovane
*/

const knxLog = require('./../KnxLog');

//
// DPT3.*: 4-bit dimming/blinds control
//
exports.formatAPDU = function(value) {
  if (!value) knxLog.get().warn("DPT3: cannot write null value");
  else {
    var apdu_data = Buffer.alloc(1);
    if (typeof value == 'object' &&
      value.hasOwnProperty('decr_incr') &&
      value.hasOwnProperty('data')) {
      apdu_data[0] = (value.decr_incr << 3) + (value.data & 0b00000111);
    } else {
      knxLog.get().error("Must supply a value object of {decr_incr, data}");
    }
    return apdu_data;
  }
}

exports.fromBuffer = function(buf) {
  if (buf.length != 1) {
    knxLog.get().error("DPT3: Buffer should be 1 byte long, got", buf.length );
    return null;
  } else {
    return {
      decr_incr: (buf[0] & 0b00001000) >> 3,
      data:      (buf[0] & 0b00000111)
    }
  };
}

exports.basetype = {
  "bitlength": 4,
  "valuetype": "composite",
  "desc": "4-bit relative dimming control",
  "help": 
`// The parameter "data" indicates the relative amount of the dimming commmand (how much to dim).
// The parameter "data" can be any integer value from 0 to 7
// The parameter decr_incr:1 increases the light
// The parameter decr_incr:0 decreases the light
msg.payload={decr_incr: 1, data: 5};
return msg;`,
"helplink":"https://github.com/Supergiovane/node-red-contrib-knx-ultimate/wiki/-Sample---Dimming"
}

exports.subtypes = {
  // 3.007 dimming control
  "007": {
    "name": "Dimming control",
    "desc": "dimming control"
  },

  // 3.008 blind control
  "008": {
    "name": "Blinds control",
    "desc": "blinds control"
  }
}

/*
        2.6.3.5 Behavior
Status
off     dimming actuator switched off
on      dimming actuator switched on, constant brightness, at least
        minimal brightness dimming
dimming actuator switched on, moving from actual value in direction of
        set value
Events
    position = 0        off command
    position = 1        on command
    control = up dX     command, dX more bright dimming
    control = down dX   command, dX less bright dimming
    control = stop      stop command
    value = 0           dimming value = off
    value = x%          dimming value = x% (not zero)
    value_reached       actual value reached set value

The step size dX for up and down dimming may be 1/1, 1/2, 1/4, 1/8, 1/16, 1/32 and 1/64 of
the full dimming range (0 - FFh).

3.007 dimming control
3.008 blind control
*/