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Snow/ice sensor interface (BAS-run snow melting) · BACnet points list
Watts tekmar BACnet Snow/Ice Sensor Interface 681 BACnet points list
Updated 7 November 2026
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.
This page lists 19 BACnet objects for the Watts tekmar BACnet Snow/Ice Sensor Interface 681 — 15 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from Watts’s own free documentation, linked below.
- Manufacturer
- Watts
- Model
- tekmar BACnet Snow/Ice Sensor Interface 681
- Equipment
- Snow/ice sensor interface (BAS-run snow melting)
- Equipment type
- Thermostats, sensors & meters
- BACnet objects
- 19 (15 writable)
- Transport
- BACnet MS/TP
- Firmware
- J1297, firmware 0.0.2 (PICS)
- Also known as
- tekmar 681, 681, BACnet Snow/Ice Sensor Interface, tekmar snow ice sensor interface, J1297
Reference only, provided as-is: verify against Watts’s current documentation and the live device before use. Not official Watts information. Terms of use.
BMS integration notes: Watts tekmar BACnet Snow/Ice Sensor Interface 681
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 to map
The short list most integrators start with — enough to run the unit from a BMS. Map more as the job needs.
| Object | Name | Why | Access |
|---|---|---|---|
| AV 2 | Melt Setpoint | Slab melting setpoint, 32-95 °F | Write |
| BI 1 | Snow Detected | Snow or ice present (1 = true) | Write |
| BI 4 | Melt Pending Detected | Melt pending (1 = true) | Write |
| AI 2 | Slab Temperature | Slab temperature | Read |
| AI 3 | Slab Target Temperature | Slab target the BAS should hold | Read |
| AI 1 | Outdoor Air Temperature | Outdoor temperature | Read |
| AI 4 | Error Code | Active error code (codes 1-8) | Read |
Sensors & values from the BMS
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.
Network 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.
Watch out for
- 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.
Watts tekmar BACnet Snow/Ice Sensor Interface 681 BACnet objects
Type: AI, AO, AV, BI, BO, BV, MI/MO/MV (multi-state) · Access: Read read-only, Write writable, Command writable with a priority array.
| Description | States | |||||
|---|---|---|---|---|---|---|
| AImin | 1 | Outdoor Air Temperature | Outdoor temperature, -76 to 266 °F | °F | Read | |
| AImin | 2 | Slab Temperature | Slab sensor temperature | °F | Read | |
| AImin | 3 | Slab Target Temperature | Current slab target | °F | Read | |
| AImin | 4 | Error Code | Active error code (see manual list) | Read | ||
| AV | 1 | BAS Outdoor Air Temperature | Outdoor temperature written by the BAS | °F | Write | |
| AVmin | 2 | Melt Setpoint | Slab melting setpoint, 32-95 °F | °F | Write | |
| AV | 3 | Snow/Ice Sensitivity | Snow/ice detection sensitivity | Write | 0=Auto, 1=Min, 2=-2, 3=-1, 4=Mid, 5=+1, 6=+2, 7=Max | |
| AV | 4 | Warm Weather Shut Down | Warm weather shutdown temperature, 32-95 °F | °F | Write | |
| AV | 5 | Cold Weather Cut Off | Cold weather cut-off temperature, -30 to 50 °F | °F | Write | |
| BImin | 1 | Snow Detected | Snow or ice detected | Write | 0=False, 1=True | |
| BI | 2 | Cold Weather Cut Off | Cold weather cut-off active | Write | 0=False, 1=True | |
| BI | 3 | Warm Weather Shut Down | Warm weather shutdown active | Write | 0=False, 1=True | |
| BImin | 4 | Melt Pending Detected | Melt pending | Write | 0=False, 1=True | |
| BI | 5 | Wet Detected | Moisture detected on the sensor | Write | 0=False, 1=True | |
| BI | 6 | Sensor Mode | Snow/ice sensor type configured | Write | 0=090 Sensor Configured, 1=095 Sensor Configured | |
| BV | 1 | Outdoor Sensor Enable | Outdoor temperature source | Write | 0=BAS Outdoor Temperature, 1=Control Interface Sensor | |
| BV | 2 | Warm Weather Shut Down Type | Warm weather shutdown mode | Write | 0=Auto, 1=Setting | |
| BV | 3 | Cold Weather Cut Off Type | Cold weather cut-off mode | Write | 0=Auto, 1=Setting | |
| BV | 4 | Reset Snow Detection Request | Clear the snow detection | Write | 0=Do nothing, 1=Reset Snow Detection |
No points match these filters.
Object ID lookup: Watts tekmar BACnet Snow/Ice Sensor Interface 681 point IDs by name
AI1Outdoor Air TemperatureAI2Slab TemperatureAI3Slab Target TemperatureAI4Error CodeAV1BAS Outdoor Air TemperatureAV2Melt SetpointAV3Snow/Ice SensitivityAV4Warm Weather Shut DownAV5Cold Weather Cut OffBI1Snow DetectedBI2Cold Weather Cut OffBI3Warm Weather Shut DownBI4Melt Pending DetectedBI5Wet DetectedBI6Sensor ModeBV1Outdoor Sensor EnableBV2Warm Weather Shut Down TypeBV3Cold Weather Cut Off TypeBV4Reset Snow Detection Request
Integration 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.
Check it against the live device. A points list tells you what the controller can expose; the unit in front of you may differ by firmware or installed options. This list is provided as-is for reference only and may contain mistakes — confirming it before you write, map or commission anything is up to you (terms). Easy BACnet scans a network for BACnet IP devices from an Android phone, reads every object on the tekmar BACnet Snow/Ice Sensor Interface 681 and exports what it actually has to Excel — free. New to BACnet? Start with what a BACnet points list is and what the object types mean.
Questions about the Watts tekmar BACnet Snow/Ice Sensor Interface 681
How many BACnet points does the Watts tekmar BACnet Snow/Ice Sensor Interface 681 have?
This list has 19 BACnet objects: 4 analog inputs, 5 analog values, 6 binary inputs, 4 binary values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which Watts tekmar BACnet Snow/Ice Sensor Interface 681 BACnet points are writable?
15 of the 19 objects accept a write. Points marked Command have a priority array: a write holds until it is released, so release it back to automatic when you are done.
Where is the official Watts tekmar BACnet Snow/Ice Sensor Interface 681 BACnet documentation?
The source is BAS Integration Manual - BACnet Snow/Ice Sensor Interface 681 (IS-T-681-BAS Integration 2641), revision 2026, published free by Watts at https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/674980-source/639280181670000000/is-t-681-bas-integration-2641.pdf.
What are the minimum BACnet points to integrate the Watts tekmar BACnet Snow/Ice Sensor Interface 681?
Start with AV 2 Melt Setpoint (Slab melting setpoint, 32-95 °F); BI 1 Snow Detected (Snow or ice present (1 = true)); BI 4 Melt Pending Detected (Melt pending (1 = true)); AI 2 Slab Temperature (Slab temperature); AI 3 Slab Target Temperature (Slab target the BAS should hold); AI 1 Outdoor Air Temperature (Outdoor temperature); AI 4 Error Code (Active error code (codes 1-8)).
Can the BMS supply sensor values to the Watts tekmar BACnet Snow/Ice Sensor Interface 681?
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.
How do I check these points on the real tekmar BACnet Snow/Ice Sensor Interface 681?
Scan the network with a BACnet IP browser such as Easy BACnet, open the device and compare its object list with this table. Anything missing is usually an option that isn't installed or a point that is disabled in the controller's configuration.
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Source: BAS Integration Manual - BACnet Snow/Ice Sensor Interface 681 · IS-T-681-BAS Integration 2641 · rev. 2026. Object names, instances and units are reproduced as published; descriptions are our own.