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BACnet instance calculator · DMS502B71 VRV BACnet interface
Daikin DMS502B71 BACnet Instance Calculator (VRV)
Free browser tool · nothing is uploaded · 5 November 2026
The Daikin DMS502B71 BACnet interface gives every VRV indoor unit group the same 35-member object template. Enter the unit number to get that group's instances.
On the DMS502B71, instance = unit number x 256 + member number. The unit number (000-255) is the XXX at the end of each object name. Unit 012's setpoint (member 10, TempAdjust_012) is 12 x 256 + 10 = AV 3082.
Daikin 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 = unit number x 256 + member number
| Part | Meaning | Range |
|---|---|---|
| N | Unit number, also the XXX in the object name | 000-255 |
| member | Member number of the object in the template | 1-35 |
Units 000-063 are on DIII-Net port 1, 064-127 on port 2, and 128-255 on ports 3 and 4 (DAM411B51 option). Members 17 (centralized control) and 21 (forced system stop) only exist for units 000, 064, 128 and 192.
Worked example: unit 012
The first objects for unit 012 on the DMS502B71, worked out with the formula above:
| Object | Name (as printed) | What it is |
|---|---|---|
| BO 3073 | StartStopCommand_XXX | On/Off setting |
| BI 3074 | StartStopStatus_XXX | On/Off status |
| BI 3075 | Alarm_XXX | Alarm |
| MI 3076 | MalfunctionCode_XXX | Malfunction code |
| MO 3077 | AirConModeCommand_XXX | Operation mode setting |
| MI 3078 | AirConModeStatus_XXX | Operation mode status |
Source
Formula and objects from Design Guide - Interface for use in BACnet (DMS502B71 / DAM411B51) · EDUS72-749C (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 Daikin instance number?
On the DMS502B71, instance = unit number x 256 + member number. The unit number (000-255) is the XXX at the end of each object name. Unit 012's setpoint (member 10, TempAdjust_012) is 12 x 256 + 10 = AV 3082.
How do I find the unit number for a Daikin VRV group?
It is the three digits at the end of the object names the interface publishes (for example StartStopCommand_012), 000-255. Divide any instance by 256: the whole number is the unit, the remainder is the member.
Why do some units have no CL_Rejection or SystemForcedOff object?
Members 17 and 21 exist only once per DIII-Net line, on units 000, 064, 128 and 192.
Is this Daikin calculator official?
No. It applies the formula printed in Daikin'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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