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Rotary heat exchanger drive (energy recovery wheel) · BACnet points list
OJ Electronics OJ-DRHX rotary heat exchanger drive BACnet points list
Updated 12 November 2026
The OJ-DRHX drives the rotor of a rotary heat exchanger and has BACnet MS/TP on RS-485. Binary Values give run, alarm reset, rotor guard and other alarm flags and a rotation-OK status; Integer Values carry the setpoint, speed limits, motor and rotor speed, torque and electrical readings. BACnet MS/TP has to be switched on first, through the OJ PC tool or Modbus.
This page lists 39 BACnet objects for the OJ Electronics OJ-DRHX rotary heat exchanger drive — 6 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from OJ Electronics’s own free documentation, linked below.
- Manufacturer
- OJ Electronics
- Model
- OJ-DRHX rotary heat exchanger drive
- Equipment
- Rotary heat exchanger drive (energy recovery wheel)
- Equipment type
- Rooftop units, AHUs & DOAS
- BACnet objects
- 39 (6 writable)
- Transport
- BACnet MS/TP
- Firmware
- AOC 2.50 or later
- Also known as
- OJ-DRHX, OJ DRHX, DRHX, 67854
Reference only, provided as-is: verify against OJ Electronics’s current documentation and the live device before use. Not official OJ Electronics information. Terms of use.
BMS integration notes: OJ Electronics OJ-DRHX rotary heat exchanger drive
Enable BACnet MS/TP on the drive, write the setpoint to IV 0 and set BV 0 to run the wheel. Watch BV 17 (rotation OK), BV 3 (rotor guard alarm) and the other alarm flags; BV 1 resets alarms.
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 |
|---|---|---|---|
| BV 0 | Motor ON/OFF | Run command (1 = on); clears on any error | Write |
| IV 0 | Setpoint / PrcSet | Setpoint, 0-10000 = 0-100.00 % | Write |
| BV 1 | Reset Alarms | Alarm reset (1 = reset) | Write |
| BV 17 | Rotation OK | Rotation OK (1 = wheel turning) | Read |
| IV 15 | Rotor Speed Out | Rotor speed, x0.01 rpm | Read |
| IV 7 | Motor Speed Out | Motor speed, x0.01 rpm | Read |
| BV 3 | Rotorguard Alarm | Rotor guard alarm | Read |
| BV 10 | Internal Stop | Internal stop alarm | Read |
| BV 9 | Overload / Rotor Blocked | Overload / rotor blocked alarm | Read |
Enable & remote start
BACnet MS/TP must be enabled (OJ PC tool or Modbus coils); then BV 0 starts and stops the wheel.
Network setup
- Out of the box the drive talks Modbus (address 79, 38400 baud, no parity, 1 stop bit); BACnet MS/TP is switched on from the OJ PC tool (Alternative device communications) or through Modbus coils.
- MS/TP settings: baud 9600-115200, MAC 0-127, Max Master 1-127, device instance 0-4194302 (Modbus holding registers).
- OJ publishes an EDE file for the object list on its product page.
Watch out for
- BV 0 drops back to 0 on any error, so the BMS has to set it again after the fault is cleared.
- Do not write BV 2 = 0: it turns BACnet MS/TP off until it is re-enabled through Modbus.
OJ Electronics OJ-DRHX rotary heat exchanger drive 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 | |||||
|---|---|---|---|---|---|---|
| BVmin | 0 | Motor ON/OFF | Run command; drive clears it on any error | Write | 1=ON | |
| BVmin | 1 | Reset Alarms | Alarm reset; returns to 0 after the reset | Write | 1=Reset | |
| BV | 2 | BACnet Enable | 0 turns BACnet MS/TP off (recover via Modbus) | Write | 1=Enabled | |
| BVmin | 3 | Rotorguard Alarm | Rotor guard (rotation sensor) alarm | Read | 1=Alarm | |
| BV | 4 | V LO Alarm | Read | 1=Alarm | ||
| BV | 5 | V HI Alarm | Read | 1=Alarm | ||
| BV | 6 | I HI Alarm ( Motor out short) | Read | 1=Alarm | ||
| BV | 7 | Temperature High | Read | 1=Warning | ||
| BV | 8 | Rotorguard signal | Rotor guard pulse | Read | 1=Pulse | |
| BVmin | 9 | Overload / Rotor Blocked | Read | 1=Alarm | ||
| BVmin | 10 | Internal Stop | Read | 1=Alarm (Stop) | ||
| BV | 11 | I Limit | Read | 1=Warning | ||
| BV | 12 | EEPROM error | Read | 1=Warning | ||
| BV | 13 | Communication error MOC | Read | 1=Alarm | ||
| BV | 14 | Motor Phase Error | Read | 1=Alarm | ||
| BV | 15 | MOC in bootloader | Read | 1=Alarm | ||
| BV | 16 | Communication error IOM | Read | 1=Warning | ||
| BVmin | 17 | Rotation OK | Wheel rotation confirmed | Read | 1=OK | |
| BV | 18 | Test function active | Read | 1=Active | ||
| IVmin | 0 | Setpoint / PrcSet | Setpoint, 0-100.00 %; value x0.01 | % | Write | |
| IV | 1 | Min. Motor Speed | value x0.01 | rpm | Write | |
| IV | 2 | Max. Motor Speed | value x0.01 | rpm | Write | |
| IV | 3 | DRHX Type | DRHX size code | Nm | Read | |
| IV | 4 | MOC SW Version | value x0.01 | Read | ||
| IV | 5 | PrcOut | value x0.01 | % | Read | |
| IV | 6 | Intern Temp | value x0.01 | °C | Read | |
| IVmin | 7 | Motor Speed Out | Motor speed; value x0.01 | rpm | Read | |
| IV | 8 | V In | V | Read | ||
| IV | 9 | I Out (RMS) | mA | Read | ||
| IV | 10 | Power In | W | Read | ||
| IV | 11 | ExterSet | mW | Read | ||
| IV | 12 | Operation Day | days | Read | ||
| IV | 13 | Operation Minutes | min | Read | ||
| IV | 14 | AOC SW Version | value x0.01 | Read | ||
| IVmin | 15 | Rotor Speed Out | Rotor (wheel) speed; value x0.01 | rpm | Read | |
| IV | 16 | Torque | value x0.01 | Nm | Read | |
| IV | 17 | V DC Bus (Peak) | V | Read | ||
| IV | 18 | V Motor (Peak) | V | Read | ||
| IV | 19 | ExternSet (IOM) | mV | Read |
No points match these filters.
Object ID lookup: OJ Electronics OJ-DRHX rotary heat exchanger drive point IDs by name
BV0Motor ON/OFFBV1Reset AlarmsBV2BACnet EnableBV3Rotorguard AlarmBV4V LO AlarmBV5V HI AlarmBV6I HI Alarm ( Motor out short)BV7Temperature HighBV8Rotorguard signalBV9Overload / Rotor BlockedBV10Internal StopBV11I LimitBV12EEPROM errorBV13Communication error MOCBV14Motor Phase ErrorBV15MOC in bootloaderBV16Communication error IOMBV17Rotation OKBV18Test function activeIV0Setpoint / PrcSetIV1Min. Motor SpeedIV2Max. Motor SpeedIV3DRHX TypeIV4MOC SW VersionIV5PrcOutIV6Intern TempIV7Motor Speed OutIV8V InIV9I Out (RMS)IV10Power InIV11ExterSetIV12Operation DayIV13Operation MinutesIV14AOC SW VersionIV15Rotor Speed OutIV16TorqueIV17V DC Bus (Peak)IV18V Motor (Peak)IV19ExternSet (IOM)
Integration notes
- Integer Value objects (IV) carry scaled whole numbers; values marked x0.01 have two implied decimals.
- Object names in the Integer Value table come from its Function column.
- BV 16 and IV 19 relate to the optional IOM I/O module.
- Writing 0 to BV 2 turns BACnet MS/TP off; it comes back only through Modbus or protocol auto-detect.
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 OJ-DRHX rotary heat exchanger drive 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 OJ Electronics OJ-DRHX rotary heat exchanger drive
How many BACnet points does the OJ Electronics OJ-DRHX rotary heat exchanger drive have?
This list has 39 BACnet objects: 19 binary values, 20 integer values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which OJ Electronics OJ-DRHX rotary heat exchanger drive BACnet points are writable?
6 of the 39 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 OJ Electronics OJ-DRHX rotary heat exchanger drive BACnet documentation?
The source is OJ-DRHX BACnet MS/TP protocol (application note) (67854), revision 10/20, published free by OJ Electronics at https://ojelectronics.com/drives/wp-admin/admin-ajax.php?action=productdownload&media_id=48365800&filename=67854-11-20-OJ-DRHX-BACnet-SM-TP-protocol_GB+web.pdf&view=true.
What are the minimum BACnet points to integrate the OJ Electronics OJ-DRHX rotary heat exchanger drive?
Start with BV 0 Motor ON/OFF (Run command (1 = on); clears on any error); IV 0 Setpoint / PrcSet (Setpoint, 0-10000 = 0-100.00 %); BV 1 Reset Alarms (Alarm reset (1 = reset)); BV 17 Rotation OK (Rotation OK (1 = wheel turning)); IV 15 Rotor Speed Out (Rotor speed, x0.01 rpm); IV 7 Motor Speed Out (Motor speed, x0.01 rpm); BV 3 Rotorguard Alarm (Rotor guard alarm); BV 10 Internal Stop (Internal stop alarm); BV 9 Overload / Rotor Blocked (Overload / rotor blocked alarm).
How do I enable BMS control of the OJ Electronics OJ-DRHX rotary heat exchanger drive?
BACnet MS/TP must be enabled (OJ PC tool or Modbus coils); then BV 0 starts and stops the wheel.
How do I check these points on the real OJ-DRHX rotary heat exchanger drive?
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: OJ-DRHX BACnet MS/TP protocol (application note) · 67854 · rev. 10/20. Object names, instances and units are reproduced as published; descriptions are our own.