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RACELOGIC Support Centre

NTRIP Modem RLACS250 - Modem Configuration


This product has been discontinued.


These instructions outline the configuration method for the Racelogic NTRIP Modem RLACS250. Ensure that the SIM Card Pin has been disabled before use.


  • Windows PC or Tablet
  • NTRIP Modem Cable RLCAB139
  • NTRIP Modem Configuration Cable RLCAB140
  • NTRIP subscription
  • Racelogic NTRIP Modem RLACS250
  • Activated SIM card with Mobile Data enabled


Input 7 V DC to 24 V DC
Consumption 12 V DC: 75 mA; 18 V DC: 50 mA


Connection FME M 50 Ω antenna connector


Wireless module features
Bands Quad-Band (850/9000/1800/1900 MHz)
  Five Bands UMTS (WCDMA/FDD) 800, 850, 900, 1900 and 2100 MHz


Environmental and Physical
Size (l x w x h) 76 mm x 56 mm x 25 mm
Extended temperature range -40 °C to +75 °C
Weight 100 g (2.5 oz)
LED Functionality

Battery Level LED

  • LED Off = Battery or external power supply OK.
  • LED On = Battery or external power supply at low voltage level
modem4 (1).png

Coverage Level LED

  • When the LED is on continuously, this indicates no mobile coverage or no SIM. If there is a SIM and mobile coverage, the LED will indicate the coverage level by flashing.

Client LED

  • On power up, this LED flashes 5 times if the equipment has been previously set up as rover.
  • The LED stays ON when a connection is established with the NTRIP server.

Server LED

  • On power up, this LED flashes 5 times if the equipment has been previously set up as a server.
    However, as the NTRIP modem will always be set as a rover, this LED should never be ON continuously.
Installing SIM Card  

Remove the SIM card cover using the supplied Torx Key


Insert the SIM card into the slot

sim2 (1).png

If you need to swap the SIM card, use a coin. Please do NOT use a screwdriver

sim3 (1).png

Hardware configuration

Modem Config connection.png

Use the RLCAB139 to supply power to the NTRIP modem by connecting it to the CAN port on  VB3iSLR and the BASE Port on the NTRIP Modem.

Connect the RLCAB140 to the RADIO/ROVER port of the NTRIP Modem to the Serial Port or the USB-Serial Adapter of the PC or Tablet.

Modem Configuration

Ensure that the power is supplied to the modem and connected to the Windows PC or Tablet as shown above.

Download and run the modem configuration software available from  here. Select the PC COM port that is connected to the Modem.

modem_config_1 (1).png

The application will scan at different baud rates to automatically identify the Modem and display the current setup of the device on screen. An example of a correctly working modem connected to the NTRIP server is shown below.

modem_config_2 (1).png

coverage_level (1).jpg Is a graphic display of the coverage level. The color indicates the coverage level. (blue >75 %, green 26 to 75 %, red < 25 % and grey 0 %).


On the lower bar, there are a series of buttons (see below) which are used to configure the modem. The configuration process involves starting from the left button to the right.


casters_list (1).jpgCasters list: This button displays a list of all of the available previously configured NTRIP servers, along with the usernames and passwords of NTRIP accounts.

modem_config_3 (1).png


By pressing the edit button edit_button (1).png, the details can be edited, deleted or new servers can be added.

modem_config_4 (1).png


To add a server, click 'Add'. The fields required for connection include the Name, IP address, port, user and password. These details will be provided by your NTRIP service provider, below is an example configuration.

modem_config_5 (1).png


operator (1).pngOperator: This allows the configuration of the Modem to suit the APN Settings in different countries with cellular providers. You should contact the SIM card provider to get these settings. You can also use this website to find these details.

modem_config_6 (1).png


server_to_client (1).pngServer to Client: Pressing this button will change the configuration from 'Client' mode to 'Server' Mode or vice versa and will update the image on this button. Ensure that the button is set as shown here.

gps-jpg.png GPS: This configures the baud rate between the Modem and VB3iSLR. The settings below should be applied.

modem_config_7 (1).png


When the 'OK' button is pressed and the settings are updated, 'The NTRIP modem will restart' message will appear.



NTRIP Modem ConfigConnection.png Connection: This button enables the connection to the NTRIP server. If mobile coverage is available and the Caster setup is correct, a list of Mount Points will be available for the user to select as shown below. Check which Mount Points are available from your NTRIP service provider. The correction messages required in VB3iSLR will be RTCMv3. Once the mount point is chosen, the software will require restarting.

modem_config_9 (1).png


Now that the Modem configuration is complete, click the check box for 'Automatic Connection'. The modem will now automatically connect to the NTRIP server after the Modem is powered on, the VB3iSLR DGPS Mode and Baud Rate are setup correctly and there is mobile coverage and satellite reception.

modem_config_10 (1).png


How to find the TopNET Live server address

If you have not been given the NTRIP Caster Settings, you can install the TopNET live mobile application here and search for them.

  • Click on the key symbol in the top right and enter your TopNET subscription Username and Password.
  • Once logged in click on the network information box at the top.
  • Make a note of the server IP address and port number. (Currently and 2101 are correct for the UK)
  • Exit and close the TopNET live Mobile app.
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