The Strato Automation OS537HW is an OPENSTAT configurable BACnet wall controller with 15 I/O (5 universal inputs, 3 analog outputs, 7 binary outputs), built-in temperature and humidity sensing, and BACnet MS/TP plus BACnet/IP over Wi-Fi 6. It mounts on a standard 2 x 4 in. electrical junction box and runs on 24 VAC/VDC.
The OS537HW controls AHU, FCU, RTU, HP and WSHP equipment, with numerous configurations to fit the project. A Sensirion SHT40 sensor provides room temperature and humidity at the wall. Configuration is available from the local buttons, BACnet configuration objects, embedded web pages or Strato software tools.
Best For
- Air handling units (AHU)
- Fan coil units (FCU)
- Rooftop units (RTU)
- Heat pumps (HP)
- Water source heat pumps (WSHP)
- Projects that need BACnet/IP over the building Wi-Fi network as well as BACnet MS/TP
Warranty
Strato Automation backs the OS537HW with a 2-year manufacturer warranty.
Key Features
BACnet MS/TP and Wi-Fi 6 BACnet/IP
BTL listed BACnet Building Controller (B-BC). Connects on MS/TP (76800 bps default) and on BACnet/IP over Wi-Fi 6 at 2.4 GHz with WPA3 or WPA2 security, integrated web services and REST API support.
15 I/O on the Wall
5 universal inputs (10K thermistor Type 2 or 3, dry contact, 0-10 VDC), 3 0-10 VDC analog outputs and 7 isolated MOSFET solid state relay binary outputs rated 10 to 30 VAC, 2.0 A max.
Temperature and Humidity
Sensirion SHT40 sensor: ±1.8% RH from 25 to 75% RH (±3% RH overall) and ±0.2 °C from 0 to 60 °C.
Phone and Browser Setup
A built-in Wi-Fi access point lets a phone or laptop open the embedded web pages directly. Export a finished configuration and import it on the next controller.
ASHRAE Guideline 36
Configurable applications are ASHRAE G36 compliant, with configuration profiles for AHU, FCU, RTU, HP and WSHP equipment.
Junction Box Mount
On-board screen with 4 side buttons in a white PC-ABS UL94 V-0 enclosure that mounts on a standard 2 x 4 in. electrical junction box.
ZOT Supply is an authorized distributor of Strato Automation products.
Technical Specifications
| Identity | |
| Manufacturer | Strato Automation |
|---|---|
| Model | OS537HW |
| Product line | OPENSTAT configurable wall controller |
| I/O | |
| Total I/O | 15: 5 universal inputs (AI/BI), 3 analog outputs, 7 binary outputs |
| Power | |
| Supply | 24 VAC/VDC ±15%, Class 2 |
| Current consumption | 1.5 VA controller only; 96 VA max including binary outputs at 2 A each |
| Communication | |
| BACnet MS/TP | MS/TP device; 9600, 19200, 38400, 76800 bps (76800 default) |
| RS-485 transceiver | 1/4 load device |
| Service port | Mini USB2 for MS/TP network access |
| BACnet/IP | Wi-Fi 6, 2.4 GHz BACnet/IP module with integrated web services and REST API support |
| BTL listing | BTL listed, BACnet Building Controller (B-BC), listing BTL-31479 |
| Inputs | |
| Universal input types | 10K ohm thermistor (Type 2 or 3), dry contact, 0-10 VDC (20K ohm input impedance) |
| Input resolution | 12 bits (4096 segments) |
| Outputs | |
| Binary output type | MOSFET solid state relays, isolated; 10 to 30 VAC, 2.0 A max |
| Analog output type | 0-10 VDC linear |
| Wi-Fi | |
| Standard | Wi-Fi 6 (IEEE 802.11ax), single band 2.4 GHz |
| Security | WPA3-Personal (SAE) or WPA2, selectable |
| Radios | Access Point mode for direct phone or laptop setup; Station mode for the building Wi-Fi network |
| Range (line of sight) | Station mode up to 30 m; Access Point mode up to 12 m |
| Network notes | Broadcast SSID required (hidden SSIDs not supported); DHCP or fixed IP |
| Sensors | |
| Temperature and humidity sensor | Sensirion SHT40 |
| Humidity accuracy | ±1.8% RH @ 25 to 75% RH; ±3% RH overall |
| Temperature accuracy | ±0.2 °C @ 0 to 60 °C (±0.36 °F @ 32 to 140 °F) |
| Hardware | |
| Microprocessor | STM32 (ARM Cortex M33), 32 bits, 250 MHz |
| Memory | 2 MB non-volatile flash; 640 KB SRAM |
| Real-time clock | Built-in capacitor, one-week backup |
| Mechanical | |
| Dimensions (W x H x D) | 3.58 x 4.92 x 0.98 in. (91 x 125 x 25 mm) |
| Mounting | Standard 2 x 4 in. electrical junction box |
| Enclosure | White, PC-ABS, UL94 V-0 |
| Environment | |
| Operating temperature | 32 to 122 °F (0 to 50 °C) |
| Storage temperature | -22 to 122 °F (-30 to 50 °C) |
| Operating humidity | 10 to 90% RH, non-condensing |
| Configuration | |
| Configuration methods | Local buttons, BACnet configuration objects, embedded web pages or Strato software tools |
| Certifications | |
| Safety | UL 916 Energy Management Equipment |
| FCC | Class A digital device, pursuant to Part 15 of the FCC Rules |
| Compliance | |
| Sequences | ASHRAE Guideline 36 (G36) compliant applications |
| Energy code | Designed to support installations intended to meet California Title 24 Building Energy Efficiency Standards performance requirements when properly configured and commissioned |
| Warranty | |
| Manufacturer warranty | 2 years |
Specifications verified November 4, 2026 against the Strato Automation OS537 Spec Sheet (May 2026, rev 3), the OPENSTAT Series Wi-Fi User Guide (July 2026, rev 5) and BTL Listing BTL-31479.
Frequently Asked Questions
What is the Strato Automation OS537HW?
The OS537HW is an OPENSTAT configurable BACnet wall controller with 15 I/O (5 universal inputs, 3 analog outputs, 7 binary outputs) and built-in temperature and humidity sensing. It communicates on BACnet MS/TP and on BACnet/IP over Wi-Fi 6.
Does the OS537HW support BACnet/IP over Wi-Fi?
Yes. The OS537HW has a Wi-Fi 6 (802.11ax) BACnet/IP module on the 2.4 GHz band with WPA3-Personal or WPA2 security, and it also supports BACnet MS/TP. It is BTL listed as a BACnet Building Controller (B-BC). The network must broadcast its SSID; hidden SSIDs are not supported.
How many inputs and outputs does the OS537HW have?
15 in total: 5 universal inputs that accept a 10K thermistor (Type 2 or 3), dry contact or 0-10 VDC, 3 0-10 VDC analog outputs and 7 isolated MOSFET solid state relay binary outputs rated 10 to 30 VAC, 2.0 A max.
How accurate are the temperature and humidity readings on the OS537HW?
The Sensirion SHT40 sensor is rated ±1.8% RH from 25 to 75% RH (±3% RH overall) and ±0.2 °C from 0 to 60 °C (±0.36 °F from 32 to 140 °F).
What power does the OS537HW need?
24 VAC/VDC ±15%, Class 2. The controller alone draws 1.5 VA; maximum consumption is 96 VA including the binary outputs at 2 A each.
How do you set up the OS537HW on Wi-Fi?
Connect a phone or laptop to the controller's built-in access point, open its embedded web pages at https://192.168.4.1, then enter the building Wi-Fi network in Station mode. A finished configuration can be exported and imported on the next controller.
What warranty comes with the OS537HW?
Strato Automation provides a 2-year manufacturer warranty.
- Supported Protocols:
- BACnet MS/TP
- Supported Protocols:
- BACnet/IP
- Wireless:
- Wi-Fi 6
- Voltage:
- 24VAC/VDC
- Universal Inputs:
- 5
- Analog Outputs:
- 3
- Binary Outputs:
- 7
- Built-In Sensors:
- Temperature
- Built-In Sensors:
- Humidity
