{
 "manufacturer": "Watts",
 "manufacturer_slug": "watts",
 "model": "tekmar BACnet Snow/Ice Sensor Interface 681",
 "model_slug": "tekmar-snow-ice-sensor-interface-681",
 "aliases": [
  "tekmar 681",
  "681",
  "BACnet Snow/Ice Sensor Interface",
  "tekmar snow ice sensor interface",
  "J1297"
 ],
 "equipment_type": "Snow/ice sensor interface (BAS-run snow melting)",
 "applies_to": "tekmar (Watts) 681 interface that connects a snow/ice sensor and slab and outdoor sensors to a building automation system for snow melting.",
 "summary": "The tekmar 681 does not run the snow melting plant itself: it reads a snow/ice sensor, a slab sensor and an outdoor sensor and reports them to the BAS over BACnet MS/TP, which then runs the boiler or electric heat. It exposes the temperatures, a slab target, snow, wet and melt-pending flags, warm and cold weather limits and an error code, and the BAS can write the melt setpoint, the sensitivity and an outdoor temperature.",
 "bacnet_transport": [
  "BACnet MS/TP"
 ],
 "firmware": "J1297, firmware 0.0.2 (PICS)",
 "default_device_instance": null,
 "access_inferred": false,
 "notes": [
  "Native BACnet MS/TP, vendor ID 585 (tekmar Control Systems), protocol revision 14, device profile B-ASC.",
  "The manual marks the Binary Inputs R/W, as listed here; they are status flags.",
  "Error codes: 1 settings memory, 2 local and BAS outdoor sensor, 3 slab sensor, 4-6 snow sensor yellow/blue/brown wire, 7 snow/ice sensor, 8 snow sensor.",
  "Temperatures are in °F."
 ],
 "source": {
  "title": "BAS Integration Manual - BACnet Snow/Ice Sensor Interface 681",
  "doc_number": "IS-T-681-BAS Integration 2641",
  "revision_date": "2026",
  "url": "https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/674980-source/639280181670000000/is-t-681-bas-integration-2641.pdf"
 },
 "integration": {
  "summary": "Wire the 681 to the BACnet MS/TP trunk (A, B, Ref) and match the baud rate. The BAS reads Snow Detected, the slab temperature and slab target and runs the melting equipment itself; it can write the melt setpoint and sensitivity, and feed an outdoor temperature when BV 1 is set to the BAS source.",
  "minimum_points": [
   {
    "ref": "AV 2",
    "name": "Melt Setpoint",
    "why": "Slab melting setpoint, 32-95 °F"
   },
   {
    "ref": "BI 1",
    "name": "Snow Detected",
    "why": "Snow or ice present (1 = true)"
   },
   {
    "ref": "BI 4",
    "name": "Melt Pending Detected",
    "why": "Melt pending (1 = true)"
   },
   {
    "ref": "AI 2",
    "name": "Slab Temperature",
    "why": "Slab temperature"
   },
   {
    "ref": "AI 3",
    "name": "Slab Target Temperature",
    "why": "Slab target the BAS should hold"
   },
   {
    "ref": "AI 1",
    "name": "Outdoor Air Temperature",
    "why": "Outdoor temperature"
   },
   {
    "ref": "AI 4",
    "name": "Error Code",
    "why": "Active error code (codes 1-8)"
   }
  ],
  "enable": null,
  "heartbeat": null,
  "remote_sensors": "With BV 1 Outdoor Sensor Enable at 0, the 681 uses the outdoor temperature the BAS writes to AV 1; at 1 it uses its own outdoor sensor.",
  "setup": [
   "MS/TP MAC address 0-127, default 60.",
   "Baud 9600-115200, default 76800; even parity, 1 stop bit.",
   "Wire A, B and Ref to the BACnet A, B and ground; do not connect the BACnet ground to the 681 ground screws.",
   "Device Communication Control password is tekmar1151."
  ],
  "gotchas": [
   "The 681 only senses and reports; the BAS must run the boiler, pumps or electric heat.",
   "Reset Snow Detection Request (BV 4) clears a detected snow condition."
  ]
 },
 "points": [
  {
   "type": "AI",
   "instance": 1,
   "name": "Outdoor Air Temperature",
   "description": "Outdoor temperature, -76 to 266 °F",
   "units": "°F",
   "access": "R",
   "states": ""
  },
  {
   "type": "AI",
   "instance": 2,
   "name": "Slab Temperature",
   "description": "Slab sensor temperature",
   "units": "°F",
   "access": "R",
   "states": ""
  },
  {
   "type": "AI",
   "instance": 3,
   "name": "Slab Target Temperature",
   "description": "Current slab target",
   "units": "°F",
   "access": "R",
   "states": ""
  },
  {
   "type": "AI",
   "instance": 4,
   "name": "Error Code",
   "description": "Active error code (see manual list)",
   "units": "",
   "access": "R",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 1,
   "name": "BAS Outdoor Air Temperature",
   "description": "Outdoor temperature written by the BAS",
   "units": "°F",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 2,
   "name": "Melt Setpoint",
   "description": "Slab melting setpoint, 32-95 °F",
   "units": "°F",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 3,
   "name": "Snow/Ice Sensitivity",
   "description": "Snow/ice detection sensitivity",
   "units": "",
   "access": "W",
   "states": "0=Auto, 1=Min, 2=-2, 3=-1, 4=Mid, 5=+1, 6=+2, 7=Max"
  },
  {
   "type": "AV",
   "instance": 4,
   "name": "Warm Weather Shut Down",
   "description": "Warm weather shutdown temperature, 32-95 °F",
   "units": "°F",
   "access": "W",
   "states": ""
  },
  {
   "type": "AV",
   "instance": 5,
   "name": "Cold Weather Cut Off",
   "description": "Cold weather cut-off temperature, -30 to 50 °F",
   "units": "°F",
   "access": "W",
   "states": ""
  },
  {
   "type": "BI",
   "instance": 1,
   "name": "Snow Detected",
   "description": "Snow or ice detected",
   "units": "",
   "access": "W",
   "states": "0=False, 1=True"
  },
  {
   "type": "BI",
   "instance": 2,
   "name": "Cold Weather Cut Off",
   "description": "Cold weather cut-off active",
   "units": "",
   "access": "W",
   "states": "0=False, 1=True"
  },
  {
   "type": "BI",
   "instance": 3,
   "name": "Warm Weather Shut Down",
   "description": "Warm weather shutdown active",
   "units": "",
   "access": "W",
   "states": "0=False, 1=True"
  },
  {
   "type": "BI",
   "instance": 4,
   "name": "Melt Pending Detected",
   "description": "Melt pending",
   "units": "",
   "access": "W",
   "states": "0=False, 1=True"
  },
  {
   "type": "BI",
   "instance": 5,
   "name": "Wet Detected",
   "description": "Moisture detected on the sensor",
   "units": "",
   "access": "W",
   "states": "0=False, 1=True"
  },
  {
   "type": "BI",
   "instance": 6,
   "name": "Sensor Mode",
   "description": "Snow/ice sensor type configured",
   "units": "",
   "access": "W",
   "states": "0=090 Sensor Configured, 1=095 Sensor Configured"
  },
  {
   "type": "BV",
   "instance": 1,
   "name": "Outdoor Sensor Enable",
   "description": "Outdoor temperature source",
   "units": "",
   "access": "W",
   "states": "0=BAS Outdoor Temperature, 1=Control Interface Sensor"
  },
  {
   "type": "BV",
   "instance": 2,
   "name": "Warm Weather Shut Down Type",
   "description": "Warm weather shutdown mode",
   "units": "",
   "access": "W",
   "states": "0=Auto, 1=Setting"
  },
  {
   "type": "BV",
   "instance": 3,
   "name": "Cold Weather Cut Off Type",
   "description": "Cold weather cut-off mode",
   "units": "",
   "access": "W",
   "states": "0=Auto, 1=Setting"
  },
  {
   "type": "BV",
   "instance": 4,
   "name": "Reset Snow Detection Request",
   "description": "Clear the snow detection",
   "units": "",
   "access": "W",
   "states": "0=Do nothing, 1=Reset Snow Detection"
  }
 ],
 "page": "https://easybacnet.com/bacnet-points-lists/watts/tekmar-snow-ice-sensor-interface-681",
 "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"
}