Cross Trainer Data (0x2ACE): byte layout
GATT characteristic · org.bluetooth.characteristic.cross_trainer_data · read from the Bluetooth SIG’s repository on 2026-10-17 · commit 408f4a0 (2026-10-14)
Cross Trainer Data is Bluetooth GATT characteristic 0x2ACE, org.bluetooth.characteristic.cross_trainer_data in the Bluetooth SIG's assigned numbers. The SIG's GATT Specification Supplement file lays its value out as 21 fields: Flags, Instantaneous Speed, Average Speed, Total Distance, Steps Per Minute and 16 more. The first, Flags, is a boolean[24]; 20 of the others are present only when a bit of it is set as the field's text states, so after the first of those, a field's offset depends on which bits are set.
- UUID
- 0x2ACE
- Identifier
org.bluetooth.characteristic.cross_trainer_data- The SIG’s description
- The Cross Trainer Data characteristic is used to represent data related to cross trainer activity.The structure of this characteristic is defined below.
- Service the SIG’s files tie it to
- None: no file in the repository lists this characteristic under a service.
- Source file
- gss/org.bluetooth.characteristic.cross_trainer_data.yaml
Byte layout: 21 fields
In the order the SIG’s structure lists them. Type and size are as published; sizes count octets except where a struct is marked as sized in bits. The offset is printed only where every earlier field has a fixed size; where an earlier field can be absent or vary, the cell names what it depends on. “Present when” is read from the field’s own “Present if” line, shown in full in the field notes below.
| Offset | Field | Type | Size | Present when | Unit |
|---|---|---|---|---|---|
| 0 | Flags | boolean[24] | 3 | Always (fixed size) | — |
| 3 | Instantaneous Speed | uint16 | 0 or 2 | Bit 0 of Flags is 0 | velocity (kilometre per hour)org.bluetooth.unit.velocity.kilometre_per_hour |
| Depends on Flags (bit 0) | Average Speed | uint16 | 0 or 2 | Bit 1 of Flags is 1 | velocity (kilometre per hour)org.bluetooth.unit.velocity.kilometre_per_hour |
| Depends on Flags (bits 0 and 1) | Total Distance | uint24 | 0 or 3 | Bit 2 of Flags is 1 | length (metre)org.bluetooth.unit.length.metre |
| Depends on Flags (bits 0, 1 and 2) | Steps Per Minute | uint16 | 0 or 2 | Bit 3 of Flags is 1 | step (per minute)org.bluetooth.unit.step_per_minute |
| Depends on Flags (bits 0, 1, 2 and 3) | Average Step Rate | uint16 | 0 or 2 | Bit 3 of Flags is 1 | step (per minute)org.bluetooth.unit.step_per_minute |
| Depends on Flags (bits 0, 1, 2 and 3) | Stride Count | uint16 | 0 or 2 | Bit 4 of Flags is 1 | unitlessorg.bluetooth.unit.unitless |
| Depends on Flags (bits 0, 1, 2, 3 and 4) | Positive Elevation Gain | uint16 | 0 or 2 | Bit 5 of Flags is 1 | length (metre)org.bluetooth.unit.length.metre |
| Depends on Flags (bits 0, 1, 2, 3, 4 and 5) | Negative Elevation Gain | uint16 | 0 or 2 | Bit 5 of Flags is 1 | length (metre)org.bluetooth.unit.length.metre |
| Depends on Flags (bits 0, 1, 2, 3, 4 and 5) | Inclination | sint16 | 0 or 2 | Bit 6 of Flags is 1 | percentageorg.bluetooth.unit.percentage |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5 and 6) | Ramp Setting | sint16 | 0 or 2 | Bit 6 of Flags is 1 | plane angle (degree)org.bluetooth.unit.plane_angle.degree |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5 and 6) | Resistance Level | uint8 | 0 or 1 | Bit 7 of Flags is 1 | unitlessorg.bluetooth.unit.unitless |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6 and 7) | Instantaneous Power | sint16 | 0 or 2 | Bit 8 of Flags is 1 | power (watt)org.bluetooth.unit.power.watt |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7 and 8) | Average Power | sint16 | 0 or 2 | Bit 9 of Flags is 1 | power (watt)org.bluetooth.unit.power.watt |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9) | Total Energy | uint16 | 0 or 2 | Bit 10 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10) | Energy Per Hour | uint16 | 0 or 2 | Bit 10 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10) | Energy Per Minute | uint8 | 0 or 1 | Bit 10 of Flags is 1 | energy (kilogram calorie)org.bluetooth.unit.energy.kilogram_calorie |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10) | Heart Rate | uint8 | 0 or 1 | Bit 11 of Flags is 1 | period (beats per minute)org.bluetooth.unit.period.beats_per_minute |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11) | Metabolic Equivalent | uint8 | 0 or 1 | Bit 12 of Flags is 1 | metabolic equivalentorg.bluetooth.unit.metabolic_equivalent |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12) | Elapsed Time | uint16 | 0 or 2 | Bit 13 of Flags is 1 | time (second)org.bluetooth.unit.time.second |
| Depends on Flags (bits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13) | Remaining Time | uint16 | 0 or 2 | Bit 14 of Flags is 1 | time (second)org.bluetooth.unit.time.second |
Field notes
Each field’s text in the SIG’s file, line by line.
- Flags boolean[24] · 3
- See Flags
- Instantaneous Speed uint16 · 0 or 2
- Base Unit: org.bluetooth.unit.velocity.kilometre_per_hourRepresented values: M = 1, d = -2, b = 0Unit is 1/100 of a kilometer per hourPresent if bit 0 of Flags field is set to 0
- Average Speed uint16 · 0 or 2
- Base Unit: org.bluetooth.unit.velocity.kilometre_per_hourRepresented values: M = 1, d = -2, b = 0Unit is 1/100 of a kilometer per hourThe Average Speed field represents the average speed since the beginning of the training session.Present if bit 1 of Flags field is set to 1
- Total Distance uint24 · 0 or 3
- Unit: org.bluetooth.unit.length.metreThe Total Distance field represents the total distance reported by the Server since the beginning of the training session.Present if bit 2 of Flags field is set to 1
- Steps Per Minute uint16 · 0 or 2
- Unit: org.bluetooth.unit.step_per_minuteThe Step per Minute Rate field represents the average step rate of a user during a period of one minute.Present if bit 3 of Flags field is set to 1
- Average Step Rate uint16 · 0 or 2
- Unit: org.bluetooth.unit.step_per_minuteThe Average Step Rate field represents the average step rate since the beginning of the training session.Present if bit 3 of Flags field is set to 1
- Stride Count uint16 · 0 or 2
- Base Unit: org.bluetooth.unit.unitlessRepresented values: M = 1, d = -1, b = 0Unit is 1/10A stride is a pair of stepsThe Stride Count field represents the total number of strides since the beginning of the training session.Present if bit 4 of Flags field is set to 1
- Positive Elevation Gain uint16 · 0 or 2
- Unit: org.bluetooth.unit.length.metreThe Positive Elevation Gain field represents the positive elevation gain since the training session has started.Present if bit 5 of Flags field is set to 1
- Negative Elevation Gain uint16 · 0 or 2
- Unit: org.bluetooth.unit.length.metreThe Negative Elevation Gain field represents the negative elevation gain since the training session has started.Present if bit 5 of Flags field is set to 1
- Inclination sint16 · 0 or 2
- Base Unit: org.bluetooth.unit.percentageRepresented values: M = 1, d = -1, b = 0Unit is 1/10 of a percentThe Inclination field represents the current inclination of the Server. A positive value means that the user feels as if they are going uphill and a negative value means that the user feels as if they are going downhill.Present if bit 6 of Flags field is set to 1
- Ramp Setting sint16 · 0 or 2
- Base Unit: org.bluetooth.unit.plane_angle.degreeRepresented values: M = 1, d = -1, b = 0Unit is 1/10 of a degreeThe Ramp Angle Setting field represents the current setting of the ramp angle of the Server.Present if bit 6 of Flags field is set to 1
- Resistance Level uint8 · 0 or 1
- Base Unit: org.bluetooth.unit.unitlessRepresented values: M = 1, d = 1, b = 0Unit is 1The Resistance Level field represents the value of the current value of the resistance level of the Server.Present if bit 7 of Flags field is set to 1
- Instantaneous Power sint16 · 0 or 2
- Unit: org.bluetooth.unit.power.wattThe Instantaneous Power field represents the value of the instantaneous power measured by the Server.Present if bit 8 of Flags field is set to 1
- Average Power sint16 · 0 or 2
- Unit: org.bluetooth.unit.power.wattThe Average Power field represents the value of the average power measured by the Server since the beginning of the training session.Present if bit 9 of Flags field is set to 1
- Total Energy uint16 · 0 or 2
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Total Energy field represents the total expended energy of a user since the training session has started.Present if bit 10 of Flags field is set to 1
- Energy Per Hour uint16 · 0 or 2
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Energy per Hour field represents the average expended energy of a user during a period of one hour.Present if bit 10 of Flags field is set to 1
- Energy Per Minute uint8 · 0 or 1
- Unit: org.bluetooth.unit.energy.kilogram_calorieThe Energy per Minute field represents the average expended energy of a user during a period of one minute.Present if bit 10 of Flags field is set to 1
- Heart Rate uint8 · 0 or 1
- Unit: org.bluetooth.unit.period.beats_per_minuteThe Heart Rate field represents the current heart rate value of the user (e.g., measured via the contact heart rate or any other means).Present if bit 11 of Flags field is set to 1
- Metabolic Equivalent uint8 · 0 or 1
- Base Unit: org.bluetooth.unit.metabolic_equivalentRepresented values: M = 1, d = -1, b = 0Unit is 1/10 metabolic equivalentThe Metabolic Equivalent field represents the metabolic equivalent of the user.Present if bit 12 of Flags field is set to 1
- Elapsed Time uint16 · 0 or 2
- Unit: org.bluetooth.unit.time.secondThe Elapsed Time field represents the elapsed time of a training session since the training session has started.Present if bit 13 of Flags field is set to 1
- Remaining Time uint16 · 0 or 2
- Unit: org.bluetooth.unit.time.secondThe Remaining Time field represents the remaining time of a training session that has been selected.Present if bit 14 of Flags field is set to 1
Flags and value tables
The definitions the SIG’s file gives for its fields, every row as published. On a flags table the last column lists the fields whose “Present if” line names that bit.
Flags
The bits of this field are defined below.
| Bit | Description | Fields its condition names |
|---|---|---|
| 0 | More Data | Instantaneous Speed when 0 |
| 1 | Average Speed present | Average Speed when 1 |
| 2 | Total Distance present | Total Distance when 1 |
| 3 | Step Count present | Steps Per Minute when 1Average Step Rate when 1 |
| 4 | Stride Count present | Stride Count when 1 |
| 5 | Elevation Gain present | Positive Elevation Gain when 1Negative Elevation Gain when 1 |
| 6 | Inclination and Ramp Angle Setting present | Inclination when 1Ramp Setting when 1 |
| 7 | Resistance Level present | Resistance Level when 1 |
| 8 | Instantaneous Power present | Instantaneous Power when 1 |
| 9 | Average Power present | Average Power when 1 |
| 10 | Expended Energy present | Total Energy when 1Energy Per Hour when 1Energy Per Minute when 1 |
| 11 | Heart Rate present | Heart Rate when 1 |
| 12 | Metabolic Equivalent present | Metabolic Equivalent when 1 |
| 13 | Elapsed Time present | Elapsed Time when 1 |
| 14 | Remaining Time present | Remaining Time when 1 |
| 15 | Movement Direction:0 = Forward1 = Backward | — |
| 16–23 | Reserved for Future Use | — |
Guides on this site
The connected-device guides that name 0x2ACE:
Questions
- What is the UUID of the Cross Trainer Data characteristic?
- 0x2ACE. The Bluetooth SIG's characteristic_uuids.yaml lists Cross Trainer Data as 0x2ACE with the identifier org.bluetooth.characteristic.cross_trainer_data. No file in the SIG's repository ties it to a service: the repository lists service and characteristic UUIDs separately.
- Which Cross Trainer Data fields are optional?
- 20 of its 21 fields have a published size that can be zero: Instantaneous Speed (0 or 2; Present if bit 0 of Flags field is set to 0); Average Speed (0 or 2; Present if bit 1 of Flags field is set to 1); Total Distance (0 or 3; Present if bit 2 of Flags field is set to 1); Steps Per Minute (0 or 2; Present if bit 3 of Flags field is set to 1); Average Step Rate (0 or 2; Present if bit 3 of Flags field is set to 1); Stride Count (0 or 2; Present if bit 4 of Flags field is set to 1); Positive Elevation Gain (0 or 2; Present if bit 5 of Flags field is set to 1); Negative Elevation Gain (0 or 2; Present if bit 5 of Flags field is set to 1); Inclination (0 or 2; Present if bit 6 of Flags field is set to 1); Ramp Setting (0 or 2; Present if bit 6 of Flags field is set to 1); Resistance Level (0 or 1; Present if bit 7 of Flags field is set to 1); Instantaneous Power (0 or 2; Present if bit 8 of Flags field is set to 1); Average Power (0 or 2; Present if bit 9 of Flags field is set to 1); Total Energy (0 or 2; Present if bit 10 of Flags field is set to 1); Energy Per Hour (0 or 2; Present if bit 10 of Flags field is set to 1); Energy Per Minute (0 or 1; Present if bit 10 of Flags field is set to 1); Heart Rate (0 or 1; Present if bit 11 of Flags field is set to 1); Metabolic Equivalent (0 or 1; Present if bit 12 of Flags field is set to 1); Elapsed Time (0 or 2; Present if bit 13 of Flags field is set to 1); Remaining Time (0 or 2; Present if bit 14 of Flags field is set to 1). Flags (3) has a fixed size.
- What units does Cross Trainer Data use?
- The SIG's text names a unit for 20 of the 21 fields: Instantaneous Speed: velocity (kilometre per hour) (org.bluetooth.unit.velocity.kilometre_per_hour); Average Speed: velocity (kilometre per hour) (org.bluetooth.unit.velocity.kilometre_per_hour); Total Distance: length (metre) (org.bluetooth.unit.length.metre); Steps Per Minute: step (per minute) (org.bluetooth.unit.step_per_minute); Average Step Rate: step (per minute) (org.bluetooth.unit.step_per_minute); Stride Count: unitless (org.bluetooth.unit.unitless); Positive Elevation Gain: length (metre) (org.bluetooth.unit.length.metre); Negative Elevation Gain: length (metre) (org.bluetooth.unit.length.metre); Inclination: percentage (org.bluetooth.unit.percentage); Ramp Setting: plane angle (degree) (org.bluetooth.unit.plane_angle.degree); Resistance Level: unitless (org.bluetooth.unit.unitless); Instantaneous Power: power (watt) (org.bluetooth.unit.power.watt); Average Power: power (watt) (org.bluetooth.unit.power.watt); Total Energy: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Energy Per Hour: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Energy Per Minute: energy (kilogram calorie) (org.bluetooth.unit.energy.kilogram_calorie); Heart Rate: period (beats per minute) (org.bluetooth.unit.period.beats_per_minute); Metabolic Equivalent: metabolic equivalent (org.bluetooth.unit.metabolic_equivalent); Elapsed Time: time (second) (org.bluetooth.unit.time.second); Remaining Time: time (second) (org.bluetooth.unit.time.second).
- What do the bits of the Cross Trainer Data Flags field mean?
- The SIG defines them as: bit 0, More Data (Instantaneous Speed when 0); bit 1, Average Speed present (Average Speed when 1); bit 2, Total Distance present (Total Distance when 1); bit 3, Step Count present (Steps Per Minute when 1, Average Step Rate when 1); bit 4, Stride Count present (Stride Count when 1); bit 5, Elevation Gain present (Positive Elevation Gain when 1, Negative Elevation Gain when 1); bit 6, Inclination and Ramp Angle Setting present (Inclination when 1, Ramp Setting when 1); bit 7, Resistance Level present (Resistance Level when 1); bit 8, Instantaneous Power present (Instantaneous Power when 1); bit 9, Average Power present (Average Power when 1); bit 10, Expended Energy present (Total Energy when 1, Energy Per Hour when 1, Energy Per Minute when 1); bit 11, Heart Rate present (Heart Rate when 1); bit 12, Metabolic Equivalent present (Metabolic Equivalent when 1); bit 13, Elapsed Time present (Elapsed Time when 1); bit 14, Remaining Time present (Remaining Time when 1); bit 15, Movement Direction: 0 = Forward; 1 = Backward. The remaining bits are reserved for future use.
Source
Read on 2026-10-17 from gss/org.bluetooth.characteristic.cross_trainer_data.yaml and assigned_numbers/uuids/characteristic_uuids.yaml in the Bluetooth SIG’s public repository (branch main, commit 408f4a0, committed 2026-10-14), by scripts/fetch-bluetooth-gatt.mjs. The file’s notice says it is proprietary to Bluetooth SIG, that furnishing it grants no licence, and that it is subject to change without notice; it is © Bluetooth SIG, Inc., and its text is quoted here for identification. Generated by AIFitnessAPI, which is not affiliated with Bluetooth SIG; the SIG’s file remains the authority. The full notice and the conventions used on these pages are on the reference hub.