{
 "manufacturer": "Dwyer",
 "manufacturer_slug": "dwyer",
 "model": "Series DHC Digihelic differential pressure controller, BACnet MS/TP",
 "model_slug": "dhc-digihelic-differential-pressure-controller",
 "aliases": [
  "DHC",
  "Series DHC",
  "Digihelic",
  "Digihelic DHC",
  "DwyerOmega DHC",
  "DHC-xxx-xxx"
 ],
 "equipment_type": "Differential pressure sensor / controller",
 "applies_to": "Dwyer Series DHC Digihelic panel-mount differential pressure controllers with two relays, analog outputs and RS-485 set to BACnet MS/TP.",
 "summary": "The DHC Digihelic is a differential pressure gauge, transmitter and two-relay controller that can also show velocity or flow. Its RS-485 port runs Modbus RTU (factory setting) or BACnet MS/TP, picked in the Conn menu. Over BACnet it exposes pressure, derived velocity and flow, peak and valley, and all set point, alarm, relay and external input settings as writable objects.",
 "bacnet_transport": [
  "BACnet MS/TP"
 ],
 "firmware": null,
 "default_device_instance": "607000 + MS/TP address (607xxx)",
 "access_inferred": false,
 "notes": [
  "Pressure, velocity and flow units are model specific; the BACnet units property is set separately from the display units.",
  "Peak, valley, set point, alarm and output limit values use the units of the process mode picked in MV 1.",
  "The overview table prints AV 12 as \"Set Point 2 Reset\"; its property table names it \"Set Point 2 Reset Value\" (used here).",
  "Alarm and input delays (PIV 1-2) have a maximum of 3600; the manual does not print their units."
 ],
 "source": {
  "title": "Series DHC Digihelic Differential Pressure Controller - Specifications, Installation and Operating Instructions",
  "doc_number": "Bulletin P-DHC (FR# 444618-00 Rev. 1)",
  "revision_date": "3/23",
  "url": "https://assets.dwyeromega.com/manuals-do/AT_DHC_Instruction_Manual.pdf"
 },
 "integration": {
  "summary": "Pick BAC in the Prot sub menu, set an address, then read AI 1 pressure (or AV 1 / AV 2 velocity and flow). Set point, alarm and relay settings are all writable over the network if the BMS should own them.",
  "minimum_points": [
   {
    "ref": "AV 9",
    "name": "Set Point 1 Trigger Value",
    "why": "Set point 1 trigger value, process units"
   },
   {
    "ref": "AI 1",
    "name": "Pressure",
    "why": "Differential pressure"
   },
   {
    "ref": "AV 2",
    "name": "Flow",
    "why": "Airflow (flow mode)"
   },
   {
    "ref": "BV 2",
    "name": "Set Point 1 Status",
    "why": "Set point 1 active"
   },
   {
    "ref": "BV 4",
    "name": "Set Point 2 Status",
    "why": "Set point 2 active"
   },
   {
    "ref": "BV 6",
    "name": "Alarm High Limit Status",
    "why": "High alarm active"
   },
   {
    "ref": "BV 8",
    "name": "Alarm Low Limit Status",
    "why": "Low alarm active"
   }
  ],
  "enable": null,
  "heartbeat": null,
  "remote_sensors": null,
  "setup": [
   "Protocol is Modbus RTU from the factory; choose BAC in Conn > Prot to use BACnet MS/TP.",
   "Address range 0-127, factory 127; baud 9600 to 115200 or auto (factory). Parity and stop bits are fixed at none and 1 on BACnet.",
   "Device instance and device name default to 607xxx and follow the address until written over the network.",
   "DeviceCommunicationControl and ReinitializeDevice need the password \"Dwyer\"."
  ],
  "gotchas": [
   "Peak and valley (AV 3-4) cannot be reset over the network.",
   "Alarm status BVs can only be written inactive when Manual Alarm Reset (BV 9) is on and the condition has cleared.",
   "A change of bus serial settings needs a power cycle to rerun auto serial configuration."
  ]
 },
 "points": [
  {
   "type": "AI",
   "instance": 1,
   "name": "Pressure",
   "description": "Differential pressure; units model specific",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 1,
   "name": "Velocity",
   "description": "Velocity from pressure; fpm or m/s",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 2,
   "name": "Flow",
   "description": "Flow from velocity and area; cfm or m3/h",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 3,
   "name": "Peak",
   "description": "Highest process value since power-up or reset",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 4,
   "name": "Valley",
   "description": "Lowest process value since power-up or reset",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 5,
   "name": "Velocity K-Factor",
   "description": "Pitot tube K-factor, default 1.0",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 6,
   "name": "Flow Area",
   "description": "Duct cross-section area, 0.13-25.0 ft2",
   "units": "ft²",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 7,
   "name": "Process Output Low",
   "description": "Process value at minimum analog output",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 8,
   "name": "Process Output High",
   "description": "Process value at maximum analog output",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 9,
   "name": "Set Point 1 Trigger Value",
   "description": "Value at which set point 1 turns active",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 10,
   "name": "Set Point 1 Reset Value",
   "description": "Value at which set point 1 turns inactive",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 11,
   "name": "Set Point 2 Trigger Value",
   "description": "Value at which set point 2 turns active",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 12,
   "name": "Set Point 2 Reset Value",
   "description": "Value at which set point 2 turns inactive",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 13,
   "name": "Alarm High Limit",
   "description": "High alarm limit",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 14,
   "name": "Alarm Low Limit",
   "description": "Low alarm limit",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "MV",
   "instance": 1,
   "name": "Process Mode",
   "description": "Process variable for outputs and limits",
   "units": "",
   "access": "W",
   "states": "1=Pressure, 2=Velocity, 3=Flow"
  },
  {
   "type": "MV",
   "instance": 2,
   "name": "Voltage Output Range",
   "description": "Voltage output range",
   "units": "",
   "access": "W",
   "states": "1=0-10V, 2=0-5V, 3=2-10V, 4=1-5"
  },
  {
   "type": "MV",
   "instance": 3,
   "name": "Relay 1 Source",
   "description": "What drives relay 1",
   "units": "",
   "access": "W",
   "states": "1=Off, 2=Set Point 1, 3=Set Point 2, 4=Any Alarm, 5=Alarm High Limit, 6=Alarm Low Limit, 7=External Input"
  },
  {
   "type": "MV",
   "instance": 4,
   "name": "Relay 1 Action",
   "description": "Relay 1 action when active",
   "units": "",
   "access": "W",
   "states": "1=Direct, 2=Reverse"
  },
  {
   "type": "MV",
   "instance": 5,
   "name": "Relay 2 Source",
   "description": "What drives relay 2",
   "units": "",
   "access": "W",
   "states": "1=Off, 2=Set Point 1, 3=Set Point 2, 4=Any Alarm, 5=Alarm High Limit, 6=Alarm Low Limit, 7=External Input"
  },
  {
   "type": "MV",
   "instance": 6,
   "name": "Relay 2 Action",
   "description": "Relay 2 action when active",
   "units": "",
   "access": "W",
   "states": "1=Direct, 2=Reverse"
  },
  {
   "type": "MV",
   "instance": 7,
   "name": "External Input Type",
   "description": "Contact type on the external input",
   "units": "",
   "access": "W",
   "states": "1=Normally Open, 2=Normally Closed"
  },
  {
   "type": "BV",
   "instance": 1,
   "name": "Enable Set Point 1",
   "description": "Enable set point 1",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 2,
   "name": "Set Point 1 Status",
   "description": "Set point 1 active",
   "units": "",
   "access": "R",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 3,
   "name": "Enable Set Point 2",
   "description": "Enable set point 2",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 4,
   "name": "Set Point 2 Status",
   "description": "Set point 2 active",
   "units": "",
   "access": "R",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 5,
   "name": "Enable Alarm High Limit",
   "description": "Enable high alarm",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 6,
   "name": "Alarm High Limit Status",
   "description": "High alarm active; write inactive to reset (manual reset mode)",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 7,
   "name": "Enable Alarm Low Limit",
   "description": "Enable low alarm",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 8,
   "name": "Alarm Low Limit Status",
   "description": "Low alarm active; write inactive to reset (manual reset mode)",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 9,
   "name": "Manual Alarm Reset",
   "description": "Alarms latch until reset when active",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 10,
   "name": "Power Up Alarm Inhibit",
   "description": "Low alarm held off until value first rises above limit",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 11,
   "name": "Enable External Input",
   "description": "Enable the external input",
   "units": "",
   "access": "W",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "BV",
   "instance": 12,
   "name": "External Input Status",
   "description": "External input active",
   "units": "",
   "access": "R",
   "states": "0=Inactive, 1=Active"
  },
  {
   "type": "PIV",
   "instance": 1,
   "name": "Alarm Delay",
   "description": "Time an alarm condition must last, max 3600",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "PIV",
   "instance": 2,
   "name": "External Input Activation Delay",
   "description": "Time the input must be on before active, max 3600",
   "units": "",
   "access": "W",
   "states": ""
  },
  {
   "type": "PIV",
   "instance": 3,
   "name": "Damping Time",
   "description": "Measurement damping, 0-30 s; 0 = off",
   "units": "s",
   "access": "W",
   "states": ""
  }
 ],
 "page": "https://easybacnet.com/bacnet-points-lists/dwyer/dhc-digihelic-differential-pressure-controller",
 "note": "Provided as-is. Point availability varies by firmware and options; verify against the live device.",
 "disclaimer": "DISCLAIMER: reference only, provided AS IS with no warranty. May contain errors or be out of date. You must verify every point against the manufacturer's current documentation and the live device before use. easybacnet.com accepts no liability for its use and is not affiliated with the manufacturer. Terms: https://easybacnet.com/terms#content"
}