A daisy chain is built from three components, all connected with standard RJ45 CAT5/6/7 cables.

DAISY-THUM: the chained temperature & humidity sensor itself. Add one per measuring point, up to the chain maximum of your base unit.

DAISY-STARTER: connects the first sensor of the chain to the base unit and feeds power into the string.

DAISY-BOOSTER: optional inline booster that lifts the chain voltage back to 14V when it drops toward the 9V minimum on long strings.

Which one? For ceiling mounted aisle monitoring, see the DAISY-THUM-C ceiling variant. For a single measuring point connected directly to the base unit, see the ENV-THUM temperature & humidity sensor.

The entire chain appears in your network through a single base unit with a single IP address.

Chain capacity: up to 40 DAISY-THUM sensors per string on a BASE-5 base unit (firmware 9.3 or higher), and up to 80 sensors per string on a BASE-IND-6.

Cabling: sensors interconnect with standard RJ45 CAT5/6/7 patch cables. No proprietary cabling, no conduit runs back to a controller for every measuring point.

Power budget: the chain starts at 14V from the DAISY-STARTER and each sensor requires a minimum of 9V. Actual capacity varies with distance, cable quality and power source; a DAISY-BOOSTER restores the voltage on long strings.

Fewer switch ports: one uplink serves the whole chain, reducing network ports, PDU outlets and installation labour compared to per-point devices.

Per rack: ASHRAE guidance calls for measuring points at the top, middle and bottom of the rack face. With three sensors per rack, one chain covers a full row from a single base unit.

Hot & cold aisles: distribute sensors along both aisles to trend supply and return conditions, detect stratification and verify containment performance.

White space rollouts: chains scale room by room without touching the network design: each additional row is another chain, not another controller project.

Trending & alerting: every sensor reports individually, so hotspots are located to the rack, not just the room.

Resolution: temperature is resolved at 0.02°C, fine enough to trend airflow and containment changes long before thresholds are reached.

Standard accuracy: ±0.5°C for temperature (10°C to 50°C) and ±2% for relative humidity.

High accuracy option: ±0.2°C for temperature (10°C to 50°C) and ±1.6% relative humidity for sites with tighter SLAs.

Calibration certificates: optional ISO 17025 calibration certificates for temperature and NIST traceable certificates for humidity support audit and compliance trails.

Single power source: the base unit powers the entire string through the DAISY-STARTER. The base unit itself runs on PoE or 12V DC, with 24V and -48V options for telecom environments.

No per-sensor supplies: measuring points need no local power outlets, PSUs or batteries, which keeps racks clean and removes battery replacement from the maintenance schedule.

Long strings: when voltage along the chain approaches the 9V minimum, the inline DAISY-BOOSTER lifts it back to 14V so the string keeps its full length.

Independent by design: the base unit is a standalone device with its own IP address. It monitors the chain, logs readings and triggers alerts entirely on its own.

Alerting: alerts are sent via email, SNMP traps or optional SMS the moment a threshold is crossed.

No PC or cloud required: no software installation, server or Internet connectivity is needed for the sensors to operate. The platform is designed for local, on-premises operation.

Optional central software: for multi-unit sites, the optional monitoring software adds centralized dashboards, trending and reporting across base units.

Readings from every sensor on the chain are exposed through the base unit's open protocols.

BMS: Modbus TCP, BACnet IP & Modbus RTU.

NMS/DCIM: SNMP, with SNMP GET polling and SNMP traps for alerts.

IIoT: MQTT, available on BASE-6 base units.

Native RS-485 option: an optional native RS-485 (Modbus RTU) sensor version enables direct integration with your own gateways and controllers.

Details: see the API & Protocols page for current protocol availability per base unit and firmware.

Mounting options: 0U rack mount, DIN rail, magnetic or wall mount, so measuring points sit exactly where ASHRAE guidance puts them without consuming rack units.

Build: industrial grade steel enclosure, designed for indoor deployments in data center white space, server rooms and technical spaces.

Plug & play: sensors are auto-detected on the chain; adding a measuring point is a patch cable, not a project.

Versions	DAISY-THUM (rack & aisle) · DAISY-THUM-C (ceiling) · optional native RS-485 (Modbus RTU) version
Temperature range	-55°C to +125°C (-67°F to +257°F)
Humidity range	10% to 90% relative humidity
Resolution	0.02°C (temperature)
Accuracy	±0.5°C (10°C to 50°C) & ±2% RH standard · ±0.2°C & ±1.6% RH high accuracy option
Calibration	Optional ISO 17025 certificate (temperature) · NIST traceable certificate (humidity)
Chain capacity	Up to 40 sensors per string on BASE-5 (firmware 9.3+) · up to 80 on BASE-IND-6 · minimum 9V at each sensor, 14V chain feed, DAISY-BOOSTER for long strings
Cabling & power	RJ45 CAT5/6/7 between sensors · powered over the chain from the base unit (PoE, 12V DC, optional 24V or -48V)
Mounting	0U rack · DIN rail · magnetic · wall · industrial steel enclosure, indoor use
Protocols (via base unit)	BMS: Modbus TCP, BACnet IP & Modbus RTU · NMS/DCIM: SNMP · IIoT: MQTT (on BASE-6)

For complete and current figures, always refer to the DAISY-THUM data sheet.