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BACnet instance calculator · BMS-IFBN1281U BN interface
Toshiba BMS-IFBN1281U BACnet Instance Calculator
Free browser tool · nothing is uploaded · 5 November 2026
Toshiba Carrier's BN interface gives every indoor unit the same block of objects, numbered from the unit's central control address and a fixed function code.
On the BMS-IFBN1281U, instance = central control address x 256 + function code. The ON/OFF status code is 0x02, so unit 10's run status is 10 x 256 + 2 = BI 2562 and its setpoint command (code 0x84) is AO 2692.
Toshiba calculator
The calculator needs JavaScript. The formula and a worked example are below.
Which unit does this instance belong to?
How the numbers are built
instance = central control address x 256 + function code
| Part | Meaning | Range |
|---|---|---|
| n | Central control address of the indoor unit (*** in the object name) | 1-128 (64 on TCC-LINK) |
| code | Function code of the object | 0x01-0xEF |
Every indoor unit needs a central control address before the BN interface's air conditioner search mode will find it; objects only exist for units it found.
Worked example: central control address 10
The first objects for central control address 10 on the BMS-IFBN1281U, worked out with the formula above:
| Object | Name (as printed) | What it is |
|---|---|---|
| BI 2562 | State/BI_*** | Indoor unit on/off status |
| BO 2690 | State/BO_*** | Indoor unit start/stop command |
| MI 2563 | Mode/MI_*** | Operation mode status |
| MO 2691 | Mode/MO_*** | Operation mode command |
| MI 2565 | Fan/MI_*** | Fan speed status |
| MO 2693 | Fan/MO_*** | Fan speed command |
Source
Formula and objects from BN interface Service Manual, BMS-IFBN1281U-E / BMS-IFBN1281U-TR · A10-2301-3 · rev. 2024-05 (Revision 3) (manufacturer document ↗), re-typed in our points list. Object names are shown as printed.
Check it against the live device. The calculator applies the formula from the manufacturer’s documentation; the gateway in front of you may expose fewer objects or use other numbers after a firmware change. Easy BACnet scans a network for BACnet IP devices from an Android phone and reads every object on them — a quick way to confirm one unit before you map a whole building.
Questions
How do I work out a Toshiba instance number?
On the BMS-IFBN1281U, instance = central control address x 256 + function code. The ON/OFF status code is 0x02, so unit 10's run status is 10 x 256 + 2 = BI 2562 and its setpoint command (code 0x84) is AO 2692.
What is the BN interface's own device instance?
By default it is the last byte of its IP address (100 at the factory IP), so changing the IP changes the device instance unless 'User Setting' is chosen in the engineering tool.
Is this Toshiba calculator official?
No. It applies the formula printed in Toshiba's own documentation to the points list in our library. Confirm the numbers against a scan of the live device before you map or write anything.
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