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== Dead Reckoning ==
=External RTK coordinate via CAN/RS232 interface with FMC650=
'''Dead Reckoning''' is a navigation technique used to estimate current position of vehicle  , direction of movement, based on its previous position and known speed.  It uses additional sensor data to correct the position received from GNSS receiver.<br>
==Overview==
Activating '''RTK (Real-Time Kinematic)''' coordinate acquisition enables the FMC650 device to process RTK data from CAN.
When configured, the RTK module can provide high-precision coordinates using: 
* External RTK receiver via RS232
* External RTK data via CAN
* Internal GNSS receiver (GNSs) as fallback (does not has RTK)
The device automatically chooses the best available source based on configuration and data quality.   


Usage of Dead Reckoning is essential in scenarios where GNSS signal is weak or unavailable, such as underground parking lots, tunnels or dense forests.<br>
The following specifications indicate the minimum firmware and configurator version requirement to use RTK coordinate acquisition via CAN on FMC650.


Key points to understand before utilizing the Dead Reckoning functionality:
*Platform: FM65 
* Installation
* '''Device''': FMC650 
* Configuration
* '''Firmware version''': 03.01.03.Rev.228
* Alignment
* '''Configurator version''': B.FMX6_R.192


=== <u>Prerequisites and Important Settings</u> ===
==Method of Operation==
* Device mounting quality  – Correct device mounting is critical for Dead Reckoning operation. Improper mounting may result in incorrect sensor data and unreliable Dead Reckoning performance.
When the RTK option is enabled, the device always tries to use RTK sources first and falls back to internal GNSS if needed.
* Dead Reckoning alignment maintenance – If Dead Reckoning alignment parameters are no longer valid, send the DR_RESET command and perform calibration.
* Electric and hybrid vehicles – For electric and hybrid vehicles, DIN1 should be used for movement detection to ensure correct Dead Reckoning operation.
* Dead Reckoning is not supported for two‑wheeled vehicles (e.g., motorcycles, scooters).


=== <u>Basic Operation</u> ===
'''Source priority'''
#'''RS232 (primary RTK source)'''
#:*The device checks whether any COM port (COM1 or COM2) is configured in RTK mode. 
#:*If at least one COM port is configured for RTK and valid data is present, coordinates are taken from RS232. 
#'''CAN RTK (secondary RTK source)'''
#:*If RS232 RTK data is not available or is invalid, the device checks the CAN RTK status. 
#:*If valid CAN RTK data is available, coordinates are taken from CAN. 
#:*A timing check is applied if the time difference between received CAN RTK frames is greater than 2 seconds. The device automatically switches to the internal GNSS receiver (GNS) to keep coordinates up to date.
#'''Internal GNSS (GNS) Fallback'''
#:*If neither RS232 nor CAN provide valid RTK data, the device uses the internal GNSS receiver (GNS) for coordinates. 
#'''RTK Disabled'''
#:*If the RTK option is disabled, coordinates are always taken from the internal GNSS receiver.


'''<u>Installation</u>'''<br>
'''RTK data from CAN'''


The device must be mounted firmly in the vehicle, with good visibility of the sky. Failure to ensure proper mounting will result in inability to calibrate the device or inaccurate position estimation. Following examples ensure that the GNSS antenna is facing towards the sky and there are no physical obstacles, like metal plates, wires, are blocking the GNSS signal.
When CAN is used as the RTK source, the device reads: 
*'''Latitude''' 
*'''Longitude''' 
*'''Altitude''' 
*'''Ground speed'''  
*'''Course'''


Good '''mounting''' examples ( <span style="color:red">'''If vehicle has a heated windshield, you should look for an alternative mounting location in the trunk, on some sturdy metal closer to backseat window'''</span>):<br>
These values are taken from standard CAN messages designed for GNSS/RTK data. Exact PGNs and signal layouts depend on whether external RTK/ECD/ISOBUS system is being used.
<div style="display: flex; flex-direction: row;">
[[File:FTC927 under the front dashboard in the middle of the car.jpg|thumb|left|280px|link=Special:Redirect/file/FTC927 under the front dashboard in the middle of the car.jpg|Dashboard in the middle of the car mount]]
[[File:FTC927 beneath the speedometer panel.jpg|thumb|left|300px|link=Special:Redirect/file/FTC927 beneath the speedometer panel.jpg|Beneath the speedometer panel]]
[[File:FTC927 above the glove box.jpg|thumb|left|300px|link=Special:Redirect/file/FTC927 above the glove box.jpg|Above glove box]]
</div>


Bad '''mounting'''  examples:<br>
==Configurator Setup== 
<div style="display: flex; flex-direction: row;">
This section describes how to enable RTK as a location source and configure RS232 and CAN usage through the Configurator.
[[File:Dead Reckoning Unwanted movements will be detected by the IMU.png|thumb|left|280px|link=Special:Redirect/file/Dead Reckoning Unwanted movements will be detected by the IMU.png|Unwanted movements will be detected by the IMU]]
[[File:Dead Reckoning Metal parts above the mount.png|thumb|left|300px|link=Special:Redirect/file/Dead Reckoning Metal parts above the mount.png|Metal parts above the mount]]
[[File:Dead Reckoning vibration could cause unwanted device movements.png|thumb|left|300px|link=Special:Redirect/file/Dead Reckoning vibration could cause unwanted device movements.png|Places, where vibration could cause unwanted device movements]]
</div>


'''<u>Configuration</u>'''<br>
'''Enabling RTK as a location source'''
[[File:Source Location from RTK.png|right]]
#Open the Configurator and connect to the FMC650 device.
#Navigate to the System tab. 
#Find the option “Source Location from RTK” in the '''System Settings''' section.
#Set this option to '''Enable'''.


[[File:Dead Recknonig TCT panel_2.png|right|500px]]
When enabled, the device will use RTK data from RS232/CAN if available, with automatic fallback to internal GNSS.


''The Dead Reckoning feature is configurable via the Dead Reckoning section in the GNSS settings group under System view in TCT.''
For advanced configuration (e.g. via commands):


Parameter list can be found [[{{{model}}}_System#Parameter_list|here]].
Source Location from RTK <br>
'''Parameter ID:''' 55000 <br>
'''Values:''' 
*'''0''' – Disabled (device uses only internal GNSS) 
*'''1''' – Enabled (device uses RTK sources if available)


===== Dead Reckoning alignment status =====
Configuring RS232 for RTK Use 
If you plan to use an external RTK receiver via RS232: 
#Open the RS232/RS485 tab in the Configurator. 
#For COM1 or COM2 (or both), set the mode to RTK.


The Dead Reckoning alignment status is a 1-byte AVL ID (1433) that indicates the current status of the Dead Reckoning alignment. The possible values are:<br>
Relevant parameter IDs:
* '''0''' - Unknown: Dead Reckoning status is unknown.
*'''COM1 mode''' – Parameter ID 151 
* '''1''' - Init: Dead Reckoning alignment is initializing.
*'''COM2 mode''' – Parameter ID 173 
* '''2''' - Coarse: Dead Reckoning is in alignment stage.
*'''RTK mode''' – Value 60 
* '''3''' - Stable: Dead Reckoning alignment stage has been completed. Estimation stage is in progress.
If at least one COM port is configured to RTK mode and valid RTK data is received, the device will use RS232 as the main coordinate source.
* '''99''' - Standby: Dead Reckoning is in standby mode ('''NOTE''': this status is availabe with 3.7.X or newer firmware version)


===== Turning alignment =====
[[File:RS232 settings - RTK.png|right]]
The turning alignment is a 1-byte AVL ID ('''1434''') that indicates the current percentage of the turning alignment of the device.


===== Straight alignment =====
'''Using CAN as the RTK Source'''  
The straight alignment is a 1-byte AVL ID ('''1435''') that indicates the current percentage of the straight alignment of the device.
CAN-based RTK is used in the following cases: 
'''
*None of the RS232 COM ports are configured in RTK mode, or 
*RS232 RTK data is not valid or not present. 
When those conditions are met and valid CAN RTK data is received: 
*The device uses CAN as the coordinate source. 
*The device continuously monitors the time between RTK messages. 
*If CAN RTK messages are delayed by more than 2 seconds, the device automatically reverts to internal GNSS to avoid stale coordinates.
<br>
RTK data taken from CAN includes: 
*'''Latitude 
*'''Longitude 
*'''Altitude 
*'''Ground speed 
*'''Course 


'''<u>Alignment</u>'''<br>
Configuration of RTK over CAN (e.g. PGN, source address, bitrate) depends on your external CAN/ISOBUS/RTK infrastructure and should follow that system’sdocumentation.
Once device mounting adheres to the guidelines, alignment can be performed. The device '''must finish''' a specific alignment process to '''determine''' its mounting orientation. During this process, there are specific conditions that must be met:
# The device must be '''stationary''' with clear sky visibility for at least 3 minutes.
<!--# A great number of '''left and right''' turns must be performed.-->
# Vehicle speed during alignment should be between 10 km/h and 100 km/h, with varying speeds preferred over extended constant-speed driving.
# Avoid driving in underground tunnels or areas with poor GNSS signal, otherwise alignment needs to be restarted from the second step.
[[File:Dead Reckoning TCT Swift .png|right|400px]]


=== <u>Standby mode</u> ===
'''ISOBUS Data Visibility''' 
When used in ISOBUS or similar environments: 
[[File:ISOBUS - RTK.png]]
*RTK-related data from CAN is visible in the ISOBUS section of the Configurator. 


Standby Mode preserves Dead Reckoning calibration indefinitely, ensuring accurate position estimation after extended GNSS outages (e.g., a week in underground parking), and supports unlimited duration in this mode while maintaining full calibration integrity.
*This allows you to verify that RTK data is being received and interpreted correctly by the device.


Standby Mode has two behavior options:
==Active Location Source Monitoring==
* '''Realignment''' – Calibration alignment is discarded after the Standby Timeout period.
To understand which source is currently being used for position data, you can check the '''Location Source''' parameter.
* '''Preserve alignment''' – Calibration alignment is retained during prolonged stationary periods.


'''Location Source Values'''


'''<u>Prerequisites and important Settings</u>'''<br>
In the Configurator: 
* If the device is remounted, send the DR_Reset SMS command and perform a full recalibration. This ensures all orientation- and sensor alignment parameters are refreshed, preventing inaccurate Dead Reckoning calculations after the installation change.
#Navigate to the '''I/O''' tab (or equivalent I/O monitoring view).
#Find the parameter '''Location Source'''.
[[File:Location source.png]]


'''<u>Basic Operation</u>'''<br>
Possible values:


'''Entering Standby Mode'''
*'''0 – GNS'''
Location is taken from the internal GNSS receiver. This is the default when RTK is disabled or when no valid RTK data is available.


The device can enter Standby Mode in two scenarios:
*'''1 – RS232'''
* No movement detected
Location is taken from the RTK receiver connected via RS232.
If the device detects absence of movement, Dead Reckoning enters Standby Mode after the timeout defined by '''Standby timeout (ID 124)''' elapses.
* Device enters sleep mode
When the device transitions into sleep mode, the GNSS receiver is switched to power saving mode.


Before GNSS powers down, Dead Reckoning enters Standby Mode '''immediately''', the scenario is paused, and the device proceeds into sleep mode.
*'''2 – CAN'''
Location is taken from RTK data arriving over CAN.  


'''Exiting Standby Mode'''
*'''3 – Err'''
Location is taken from the internal GNSS receiver, but this status indicates that RTK data from RS232 and/or CAN is invalid or unavailable. This helps distinguish normal GNSS use from “RTK expected but not available” situations.


Standby Mode can be exited in the following cases:
This parameter is used for diagnostics and for confirming that your device is using the intended RTK source.
* Movement is detected
When movement is detected, the device exits Standby Mode and resumes normal Dead Reckoning operation. If '''no movement is detected''', Dead Reckoning remains in Standby Mode.


==NMEA Fix Type Monitoring (RS232 RTK Only)==
When RTK coordinates are received via RS232, you can also monitor the NMEA Fix Type to understand the quality of the GNSS/RTK fix. 


=== <u>Key Performance Indicators (based on performed tests)</u> ===
'''Configurator Steps'''
* '''GNSS denied operation (1 km)'''
#Open the Configurator. 
** When driving 1 km without a GNSS signal (including 15–20 turns), the positional error is ≤ 25 m, achieved in at least 8 out of 10 field tests.<br>
#Go to the I/O tab (or relevant section).
** Dead Reckoning continues operating beyond 1 km; however, positional error may increase after this threshold.<br>
#Locate the parameter '''NMEA Fix Type'''.  


* '''Recovery after DR Standby (Sleep Mode)'''
[[File:NMEA Fix Type.png]]
** After exiting DR Standby (Sleep Mode), the system correctly reconstructs the driven route for up to 5 minutes or 1000 m, with a positional error of ≤ 50 m, achieved in at least 8 out of 10 field tests.<br>


* '''Real world driving variability'''
'''Note:''' This parameter is '''only available when coordinate data is received via RS232 RTK'''.
** Real world driving conditions may vary and can impact performance results.


=== <u>Limitations, Edge Cases & Additional Notes</u> ===
'''NMEA Fix Type Values'''
There are some important things to keep in mind when using the Dead Reckoning functionality. The algorithm tries to correct for these issues, but sometimes they can still affect how well Dead Reckoning works.
* '''Loss of alignment during drifting''' – Dead Reckoning alignment will be lost during drifting, when the actual movement vector does not correspond to the vehicle heading. Re‑alignment is required.
* '''Overshooting''' - May occur when the vehicle travels straight for more than 50 m at speeds below 20 km/h. In such cases, positional overshoot may be observed. An example is shown in the attached image.
[[File:Dead Reckoning - Overshooting.png|300px|link=Special:Redirect/file/Dead Reckoning - Overshooting.png]]
* '''Position accuracy may decrease''' - If the device cannot receive a GNSS signal for a long time, the estimated position may become less accurate. This is because the sensors inside the device can only estimate the position for a limited time without help from GNSS.
For example: If a courier spends up to 30 minutes unloading in the underground car park, DR will remain accurate. Otherwise, positioning information will become less accurate.
* '''Temperature effects''' - The accuracy of the position can change if the temperature is very different from when the device was last calibrated.
* '''Alignment reset''' - If the device loses power or goes into sleep mode, it will need to be calibrated again.


'''Tip:''' If alignment auto-save is enabled, realignment will be faster.
*'''NotValid''' - No valid GNSS fix is available.<br>


* '''Position jumps after GNSS outages''' - Multipath occurs when reflected or diffracted GNSS signals reach the receiver, causing position errors. Since Dead Reckoning depends on GNSS for continuous correction, these multipath induced inaccuracies can lead to visible position jumps, especially in urban areas with tall buildings or obstructions.
*'''GPS''' - Standard GPS fix using satellites only.<br>
[[File:GNSS Multipath.png|350px]]
 
*'''DGNSS''' - Differential GNSS fix (e.g. DGNSS, SBAS, etc.).<br>
 
*'''NotApplicable''' - Fix quality is not applicable in the current context. <br>
 
*'''RTK_Fixed''' - RTK Fixed; high-precision RTK fix (including xFill if supported by the receiver).<br>
 
*'''RTK_Float''' - RTK Float; typically, a converging RTK solution or similar intermediate status.<br>
 
*'''INS_DR''' - INS Dead Reckoning; position estimated by inertial sensors and previous GNSS/RTK data.<br> 
 
This information is beneficial for:
*Verifying that the external RTK receiver is working correctly.
*Assessing overall RTK performance and stability.
*Logging and diagnostics in advanced deployments.
 
==Parameter IDs and AVL IDs==
 
Below is a list of AVL IDs and Configurator IDs assigned to a specific item.
 
<table class="nd-othertables_2" style="width:50%; border-collapse: collapse;">
 
<tr>
<th style="width:8%; vertical-align: middle; text-align: left;">Name</th>
<th style="width:15%; vertical-align: middle; text-align: center;">Parameter ID</th>
<th style="width:5%; vertical-align: middle; text-align: center;">AVL ID</th>
</tr>


=== <u>AVL ID list</u> ===
<table class="nd-othertables_2" style="width:100%; border-collapse: collapse;">
<tr>
<tr>
<th style="width:8%; vertical-align: middle; text-align: left;">Property ID in AVL packet</th>
<td style="vertical-align: middle; text-align: center;">RTK Longitude</td>
<th style="width:15%; vertical-align: middle; text-align: center;">Property Name</th>
<td style="vertical-align: middle; text-align: center;">151790</td>
<th style="width:5%; vertical-align: middle; text-align: center;">Bytes</th>
<td style="vertical-align: middle; text-align: center;">14145</td>
<th style="width:10%; vertical-align: middle; text-align: center;">Min Value</th>
<th style="width:10%; vertical-align: middle; text-align: center;">Max Value</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Multiplier</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Units</th>
<th style="width:32%; vertical-align: middle; text-align: left;">Description</th>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1433</td>
<td style="vertical-align: middle; text-align: center;">RTK Latitude</td>
<td style="vertical-align: middle; text-align: center;">Dead Reckoning alignment status</td>
<td style="vertical-align: middle; text-align: center;">151800</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">14146</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">99</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">[[{{{model}}}_System#Dead_Reckoning_alignment_status|Dead Reckoning alignment status]]</td>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1434</td>
<td style="vertical-align: middle; text-align: center;">RTK Altitude</td>
<td style="vertical-align: middle; text-align: center;">Turning alignment</td>
<td style="vertical-align: middle; text-align: center;">151810</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">14147</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">100</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">%</td>
<td style="vertical-align: middle; text-align: center;">[[{{{model}}}_System#Turning_alignment|Turning alignment]]</td>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1435</td>
<td style="vertical-align: middle; text-align: center;">RTK Speed</td>
<td style="vertical-align: middle; text-align: center;">Straight alignment</td>
<td style="vertical-align: middle; text-align: center;">151820</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">14148</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">100</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">%</td>
<td style="vertical-align: middle; text-align: center;">[[{{{model}}}_System#Straight alignment|Straight alignment]]</td>
</tr>
</tr>
</table>


=== <u>Parameter list</u> ===
<table class="nd-othertables_2" style="width:100%; border-collapse: collapse;">
<tr>
<tr>
<th style="width:8%; vertical-align: middle; text-align: left;">Property ID in AVL packet</th>
<td style="vertical-align: middle; text-align: center;">RTK Angle</td>
<th style="width:15%; vertical-align: middle; text-align: center;">Property Name</th>
<td style="vertical-align: middle; text-align: center;">151830</td>
<th style="width:5%; vertical-align: middle; text-align: center;">Bytes</th>
<td style="vertical-align: middle; text-align: center;">14149</td>
<th style="width:10%; vertical-align: middle; text-align: center;">Min Value</th>
<th style="width:10%; vertical-align: middle; text-align: center;">Max Value</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Multiplier</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Units</th>
<th style="width:32%; vertical-align: middle; text-align: left;">Description</th>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">123</td>
<td style="vertical-align: middle; text-align: center;">Source Location from RTK</td>
<td style="vertical-align: middle; text-align: center;">Alignment auto-save</td>
<td style="vertical-align: middle; text-align: center;">55000</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">0</td>
</tr>
<td style="vertical-align: middle; text-align: center;">1</td>
 
<tr>
<td style="vertical-align: middle; text-align: center;">Source Location from RTK</td>
<td style="vertical-align: middle; text-align: center;">55000</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">This option saves calibration data to device memory, enabling a faster recalibration after device restart. <br> '''0''' = Disable <br> '''1''' = Enable  </td>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">124</td>
<td style="vertical-align: middle; text-align: center;">Location Source</td>
<td style="vertical-align: middle; text-align: center;">Standby timeout</td>
<td style="vertical-align: middle; text-align: center;">53050</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">10919</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">65535</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">(s) seconds</td>
<td style="vertical-align: middle; text-align: center;">The standby timeout is the time after which device will attempt to correct the position based on correction strategy.<br>  Default value = '''1800''' </td>
</tr>
</tr>
<tr>
<tr>
<td style="vertical-align: middle; text-align: center;">125</td>
<td style="vertical-align: middle; text-align: center;">NMEA Fix Type</td>
<td style="vertical-align: middle; text-align: center;">Standby mode</td>
<td style="vertical-align: middle; text-align: center;">53060</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">10920</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">-</td>
<td style="vertical-align: middle; text-align: center;">The standby mode is the mode in which the device will attempt to correct the position based on correction strategy. <br>'''0''' = Realignment<br>'''1''' = Preserve alignment</td>
</tr>
</tr>
</table>

Revision as of 14:58, 14 April 2026

External RTK coordinate via CAN/RS232 interface with FMC650

Overview

Activating RTK (Real-Time Kinematic) coordinate acquisition enables the FMC650 device to process RTK data from CAN. When configured, the RTK module can provide high-precision coordinates using:

  • External RTK receiver via RS232
  • External RTK data via CAN
  • Internal GNSS receiver (GNSs) as fallback (does not has RTK)

The device automatically chooses the best available source based on configuration and data quality.

The following specifications indicate the minimum firmware and configurator version requirement to use RTK coordinate acquisition via CAN on FMC650.

  • Platform: FM65
  • Device: FMC650
  • Firmware version: 03.01.03.Rev.228
  • Configurator version: B.FMX6_R.192

Method of Operation

When the RTK option is enabled, the device always tries to use RTK sources first and falls back to internal GNSS if needed.

Source priority

  1. RS232 (primary RTK source)
    • The device checks whether any COM port (COM1 or COM2) is configured in RTK mode.
    • If at least one COM port is configured for RTK and valid data is present, coordinates are taken from RS232.
  2. CAN RTK (secondary RTK source)
    • If RS232 RTK data is not available or is invalid, the device checks the CAN RTK status.
    • If valid CAN RTK data is available, coordinates are taken from CAN.
    • A timing check is applied if the time difference between received CAN RTK frames is greater than 2 seconds. The device automatically switches to the internal GNSS receiver (GNS) to keep coordinates up to date.
  3. Internal GNSS (GNS) Fallback
    • If neither RS232 nor CAN provide valid RTK data, the device uses the internal GNSS receiver (GNS) for coordinates.
  4. RTK Disabled
    • If the RTK option is disabled, coordinates are always taken from the internal GNSS receiver.

RTK data from CAN

When CAN is used as the RTK source, the device reads:

  • Latitude
  • Longitude
  • Altitude
  • Ground speed
  • Course

These values are taken from standard CAN messages designed for GNSS/RTK data. Exact PGNs and signal layouts depend on whether external RTK/ECD/ISOBUS system is being used.

Configurator Setup

This section describes how to enable RTK as a location source and configure RS232 and CAN usage through the Configurator.

Enabling RTK as a location source

  1. Open the Configurator and connect to the FMC650 device.
  2. Navigate to the System tab.
  3. Find the option “Source Location from RTK” in the System Settings section.
  4. Set this option to Enable.

When enabled, the device will use RTK data from RS232/CAN if available, with automatic fallback to internal GNSS.

For advanced configuration (e.g. via commands):

Source Location from RTK
Parameter ID: 55000
Values:

  • 0 – Disabled (device uses only internal GNSS)
  • 1 – Enabled (device uses RTK sources if available)

Configuring RS232 for RTK Use If you plan to use an external RTK receiver via RS232:

  1. Open the RS232/RS485 tab in the Configurator.
  2. For COM1 or COM2 (or both), set the mode to RTK.

Relevant parameter IDs:

  • COM1 mode – Parameter ID 151
  • COM2 mode – Parameter ID 173
  • RTK mode – Value 60

If at least one COM port is configured to RTK mode and valid RTK data is received, the device will use RS232 as the main coordinate source.

Using CAN as the RTK Source CAN-based RTK is used in the following cases:

  • None of the RS232 COM ports are configured in RTK mode, or
  • RS232 RTK data is not valid or not present.

When those conditions are met and valid CAN RTK data is received:

  • The device uses CAN as the coordinate source.
  • The device continuously monitors the time between RTK messages.
  • If CAN RTK messages are delayed by more than 2 seconds, the device automatically reverts to internal GNSS to avoid stale coordinates.


RTK data taken from CAN includes:

  • Latitude
  • Longitude
  • Altitude
  • Ground speed
  • Course

Configuration of RTK over CAN (e.g. PGN, source address, bitrate) depends on your external CAN/ISOBUS/RTK infrastructure and should follow that system’sdocumentation.

ISOBUS Data Visibility When used in ISOBUS or similar environments:

  • RTK-related data from CAN is visible in the ISOBUS section of the Configurator.
  • This allows you to verify that RTK data is being received and interpreted correctly by the device.

Active Location Source Monitoring

To understand which source is currently being used for position data, you can check the Location Source parameter.

Location Source Values

In the Configurator:

  1. Navigate to the I/O tab (or equivalent I/O monitoring view).
  2. Find the parameter Location Source.

Possible values:

  • 0 – GNS

Location is taken from the internal GNSS receiver. This is the default when RTK is disabled or when no valid RTK data is available.

  • 1 – RS232

Location is taken from the RTK receiver connected via RS232.

  • 2 – CAN

Location is taken from RTK data arriving over CAN.

  • 3 – Err

Location is taken from the internal GNSS receiver, but this status indicates that RTK data from RS232 and/or CAN is invalid or unavailable. This helps distinguish normal GNSS use from “RTK expected but not available” situations.

This parameter is used for diagnostics and for confirming that your device is using the intended RTK source.

NMEA Fix Type Monitoring (RS232 RTK Only)

When RTK coordinates are received via RS232, you can also monitor the NMEA Fix Type to understand the quality of the GNSS/RTK fix.

Configurator Steps

  1. Open the Configurator.
  2. Go to the I/O tab (or relevant section).
  3. Locate the parameter NMEA Fix Type.

Note: This parameter is only available when coordinate data is received via RS232 RTK.

NMEA Fix Type Values

  • NotValid - No valid GNSS fix is available.
  • GPS - Standard GPS fix using satellites only.
  • DGNSS - Differential GNSS fix (e.g. DGNSS, SBAS, etc.).
  • NotApplicable - Fix quality is not applicable in the current context.
  • RTK_Fixed - RTK Fixed; high-precision RTK fix (including xFill if supported by the receiver).
  • RTK_Float - RTK Float; typically, a converging RTK solution or similar intermediate status.
  • INS_DR - INS Dead Reckoning; position estimated by inertial sensors and previous GNSS/RTK data.

This information is beneficial for:

  • Verifying that the external RTK receiver is working correctly.
  • Assessing overall RTK performance and stability.
  • Logging and diagnostics in advanced deployments.

Parameter IDs and AVL IDs

Below is a list of AVL IDs and Configurator IDs assigned to a specific item.

Name Parameter ID AVL ID
RTK Longitude 151790 14145
RTK Latitude 151800 14146
RTK Altitude 151810 14147
RTK Speed 151820 14148
RTK Angle 151830 14149
Source Location from RTK 55000 -
Source Location from RTK 55000 -
Location Source 53050 10919
NMEA Fix Type 53060 10920
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