User Guide

Specification for Spektrum X-Bus Telemetry Sensors
Page 9 Rev E
14 INDIVIDUAL CELL MONITOR
The AirWare-based transmitters may include support for a generic multi-tap voltage monitoring device.
Spektrum does not sell a device which conforms to this telemetry standard, but is instead providing a
common interface which may be supported by third-party manufacturers.
NOTE: The Common (Ve-) connection of the X-Bus is connected to the receiver, which in an electric
model is likely connected directly to the negative terminal in the battery string. It is strongly
recommended that the voltage measurements be galvanically isolated from the battery pack being
measured so as to prevent short circuits and ground loops. This isolation also permits battery packs of
more than 6 cells to be monitored accurately and without concern for wiring problems.
The “CellMon” configuration screen provides the same functions available to other devices, that is,
whether the status is actively monitored on the display. Alarms may be available for the following
conditions:
• Cell too low (any cell below threshold)
• Cell too high (any cell above threshold)
• Cell imbalance (delta of min/max cells on active inputs is above threshold)
The units and ranges for each of the fields in the telemetry message are found in the appendix in the
definition for the LIPOMON structure. The transmitter does not provide any filtering of data for any
fields.
15 ATTITUDE & MAGNETIC COMPASS
The AirWare-based transmitters may include a facility to display data from an attitude and magnetic
compass. This is currently envisioned as an information-only device which may be of use in certain
applications but unable to generate alarms. Data which is unavailable due to limitations of the sensor
hardware shall report a value of 0x7FFF to indicate “No data available.”
16 3-AXIS GYRO
The AirWare-based transmitters may include a facility to display data from a 3-axis gyro system. This
currently is envisioned as an information-only device which may be of use in certain applications, but
unable to generate alarms. Data which is unavailable due to limitations of the sensor hardware shall
report a value of 0x7FFF to indicate “No data available.”
17 USER-DEFINED DEVICES IN THE TX
The AirWare-based transmitters may include a facility to display data from user-defined sensors
according to four “user” structures defined in the Appendix. The four structures are associated with
four different identifier field values.
Transmitters may have generic screens to show the data for each structure type. The transmitters would
allow the user to specify a short title for the screen, but not for individual fields, nor would it allow
specification of units. Display of individual fields may be only turned on or off using the configuration
screen. It is up to the user to know the representation of each field shown on the transmitter for these