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DataAndConfigurationMessages / 74ExternalAuxiliaryChannels

External auxiliary channel

Channel Number74
Total Length5 bytes
ChannelData1Data2Data3Checksum

Sensor location = Data1

Channel number Default use for race applications Default use for industrial appliations
1 Throttle Position External Auxiliary channel 1
2 Lambda 1 Short Term Trim External Auxiliary channel 2
3 Lambda 2 Short Term Trim External Auxiliary channel 3
4 Lambda 1 Long Term Trim External Auxiliary channel 4
5 Lambda 2 Long Term Trim External Auxiliary channel 5
6 Fuel Inj 1 Pulse Width DGPS Corr Age
7 Fuel inj 2 PW GSM status
8 Fuel inj 3 PW GSM Rxed
9 Fuel inj 4 PW Data buffered
10 Fuel inj 5 PW Movement level
11 Fuel inj 6 PW Movement count
12 Fuel inj 7 PW Time to survey
13 Fuel inj 8 PW ADAS pos status
14 Fuel inj 1 cut GSM Txed
15 Fuel inj 2 cut GPS mode
16 Fuel inj 3 cut External Auxiliary channel 16
17 Fuel inj 4 cut Satellite status
18 Fuel inj 5 cut Corrections status
19 Fuel inj 6 cut RTCM type
20 Fuel inj 7 cut INS accuracy
21 Fuel inj 8 cut INS offset Y
22 Ignition cut INS offset X
23 ISBV 1 open INS offset Z
24 ISBV 2 Open INS speed acc
25 Nitrous INS yaw acc
26 Auxiliary 1 SB GNSS status
27 Auxiliary 2 INS convergence
28 Auxiliary 3 Sat count
29 Auxiliary 4 Sat count mod 2
30 Fuel aux temp comp SB trigger state
31 Fuel aux volt comp ACB conv

Data has a resolution of 0.1 and a range of -3276.8 to 3276.7

If Data3 & 0x80 = 1, Output = - (65536- (Data2 + Data3 x 2^8))/10
Else Output = (Data2 + Data3 x 2^8)/10

The following external auxiliary data channels are output by the SPEEDBOX, SPEEDBOX-INS, GPS2, RTK BASE STATION, RTLive and/or VIDEO4HD.


External auxiliary channel 5:

  • CPU load (RT live only)


External auxiliary channel 6:

  • Time since last differential correction (GPS2 and SPEEDBOX only)
    Outputs time in seconds since last incoming differential correction.
    A value of 60 or greater implies that corrections have effectively ceased.


External auxiliary channel 7:

RTLive connection status (RTLive only)

0 this is the state at start up
1 GSM is confirmed as powered off
2 GSM waiting for a power up
3 powering up the GSM module
4 GSM module is powered up
5 Comms between GSM module and processor are okay
6 SIM card has been detected and communicates, note this doesn't mean it has credit etc, only that there is a SIM card
7 GSM module is operational
8 detected a valid GSM radio signal, antenna is okay
9 RT live has logged onto the network, this indicates the SIM card is valid, although at this stage we do not know if connection to the internet is possible or that it has credit available etc
10 RT live is connected to the internet
11 RT Live has connected to the Race Technology server
12 RT live has logged onto a Race Technology cloud account
13 RT live unit is transmitting GPS position to the Race Technology Cloud server
14 RT live unit is receiving RTCM corrections from the Race Technology cloud server


External auxiliary channel 8:

RT Live data upload rate in Kbit/sec (RTLive only)


External auxiliary channel 9:

Number or data chunks in memory waiting for upload to the cloud server. (RTLive only)


External auxiliary channel 10:

Movement detection count (RTLive only)


External auxiliary channel 11:

  • Time since last movement in seconds (RTLive only)
  • Time to complete current high precision survey in minutes (Base station only)


External auxiliary channel 12: (Base station only)

0 Advanced GPS module not detected
1 Standard standalone 20Hz mode
2 Advanced 5Hz rover RTK mode
3 Base station mode pending but start conditions not yet met
4 Base station mode determining initial position
5 Base station mode high precision survey in progress
6 Base station mode in operation relative positioning mode
7 Base station mode in operation absolute positioning mode


External auxiliary channel 13:

  • 2nd unit status, used in 2 car ADAS applications (RT live only)
0 no 2nd unit considered
1 Receiving 2nd vehicle GPS messages on the serial port from an SB = 1
2 Uploading 2nd vehicle GPS messages to the server
3 receiving 2nd vehicle GPS messages on the serial port and the server


External auxiliary channel 14:

  • Data from from the RT live to the cloud server in kBytes/s (RTLive only)


External auxiliary channel 15:

  • GPS operation mode (RTLive only)
0 no GPS solution
1 using GPS solution from an external source uses standard (not #108) messages
2 using GPS from an external receiver using GPS message 108
3 using GPS from an external receiver using CAN **NOT implemented**
4 using standard internal GPS receiver
5 using high performance, high sensitivity internal GPS receiver
6 using internal RTK GPS receiver, currently in standard solution mode
7 using internal RTK GPS receiver, currently in float solution mode
8 using internal RTK GPS receiver, currently in RTK (2cm) solution mode


External auxiliary channel 16:

  • File index (VIDEO4HD only)
    Currently recording file index of the camera (1 to 31)
  • Last fragment upload in memory chip 2 (RTLive only)
    Note: - value should multiply by 10 to get final figure


External auxiliary channel 17:

  • GNSS observables status (GPS2 and RT Live only)
    Each 4 bits of this message indicate the number of good observables (in the range 0..15) being generated by the unit's internal GNSS receiver for each of 4 GNSS constellation/frequency combinations as indicated below:
    bits 0..3: Number of GPS L1 good observables
    bits 4..7: Number of GPS L2 good observables
    bits 8..11: Number of GLONASS L1 good observables
    bits 12..15: Number of GLONASS L2 good observables


External auxiliary channel 18:

  • Incoming corrections observables status (GPS2 and RT Live only)
    Each 4 bits of this message indicate the number of good observables (in the range 0..15) received as incoming correction data for each of 4 GNSS constellation/frequency combinations as indicated below:
    bits 0..3: Number of GPS L1 good observables
    bits 4..7: Number of GPS L2 good observables
    bits 8..11: Number of GLONASS L1 good observables
    bits 12..15: Number of GLONASS L2 good observables


External auxiliary channel 19: RTCM incoming corrections status (SPEEDBOX, GPS2 and RT Live only)

The format of this message is dependent on whether it has been transmitted by a SPEEDBOX or by a GPS2.
For the SPEEDBOX, the raw unscaled 16 bit value contains the message type of the last rtcm v3 message received. A value of zero indicates a checksum error. One auxiliary message 74.19 is output for every rtcm correction message received.
For the GPS2, auxiliary message 74.19 is output at intermittent intervals, and the raw u16 value is interpreted as a bit-field where each set bit indicates that that correction type has been received at least once since the last output of this message. The messages indicated by each bit are:
bit 0: rtcm v3 message 1001
bit 1: rtcm v3 message 1002
bit 2: rtcm v3 message 1003
bit 3: rtcm v3 message 1004
bit 4: rtcm v3 message 1005
bit 5: rtcm v3 message 1006
bit 6: rtcm v3 message 1007
bit 7: rtcm v3 message 1008
bit 8: rtcm v3 message 1009
bit 9: rtcm v3 message 1010
bit 10: rtcm v3 message 1011
bit 11: rtcm v3 message 1012
bit 12: Any other rtcm v3 message not listed above
bit 13: Any rtcm v2 message
bit 14: Reserved
bit 15: rtcm CRC error detected


External auxiliary channel 20: INS overall accuracy (SPEEDBOX-INS only)

INS overall accuracy [%]


External auxiliary channel 21: Output offset forward

Forward output offset in cm. +ve for forward, -ve for backward.


External auxiliary channel 22: Output offset right

Right output offset in cm. +ve for right, -ve for left.


External auxiliary channel 23: Output offset down'''

Down (below) output offset in cm. +ve for down, -ve for up.


External auxiliary channel 24: Combined speed accuracy (SPEEDBOX-INS only)

spd_acc [ms/s] * 100


External auxiliary channel 25: Yaw accuracy (SPEEDBOX-INS only)

yaw_acc [degrees] * 100


External auxiliary channel 26: GPS status

GPS Status codes:
0: GPS module not detected
1: Searching for satellites
2: Insufficient satellites
3: Solution aborted
4: Solution failed
5: Exceeded maximum speed or altitude
6: Unused
7: Unused
8: Unused
9: Unused
10: Lock: Position but no speed
11: Lock: Doppler speed and position
12: Lock: Carrier speed and position
20: External solution: No lock
21: External solution: Standalone (autonomous) solution
22: External solution: Solution corrected with WAAS/SBAS
23: External solution: Code differential (DGPS) solution
24: External solution: Phase differential (RTK) solution with float ambiguities
25: External solution: Phase differential (RTK) solution with integer ambiguities


External auxiliary channel 27: INS convergence (SPEEDBOX-INS only)

0->99%, INS not converged, convergence progress from 0.05 to 0.01 kf_convergence.
100%, INS converged.


External auxiliary channel 28: Number of satellites (module 1)

Number of satellites


External auxiliary channel 29: Number of satellites (module 2)

Number of satellites


External auxiliary channel 30: Trigger input state

trigger state (0 or 1)
The state of the external trigger, note that this is only provided as a convenience for testing the operation of the trigger - do not use for timing.


External auxiliary channel 31: acb_convergence (SPEEDBOX-INS only)

acb_convergence * 10000
This is the current error weighting for brake distance, this is used by the RT run processor software
Page last modified on October 12, 2020, at 03:45 PM