LM048: How do I pair two LM048s to auto-connect to each other?

A pair of LM048 or LM058 Adapters can be configured to auto-connect to each other when powered up. This procedure is calling Pairing up the adapters. This procedure is ideal when a pair of adapters are used as a serial cable replacement solution. For example a serial cable connection between a POS terminal and label printer can be replaced by a couple of LM048 Adapters paired with each other.

User needs to install LM149 Configuration Software in order to pair the adapters.


  • PC running Windows OS and LM149 Configuration Software installed
  • Inbuilt serial port or USB-RS232 cable
  • LM048 x 2 with mini USB cable or PSU
  • Serial Cable – Null Modem or Straight Wired
  • The below procedure explains the steps to pair a couple of LM048s/LM058s

Note: During the pairing procedure make sure to power the adapter with the same PSU or mini USB cable so that both adapters are not powered up at the same time.

Pairing Procedure – Step-by-step guide

Make sure the LM048 Serial Adapters are on factory settings. If not sure, please reset the adapter to factory settings by powering the adapter and pressing the RESET button for 3 seconds. The LEDs on the Adapter will blink 3 times to indicate factory reset is complete.

Important: Make sure you have nothing connected to COM1, (or the port you are using) only the LM048 otherwise pairing will fail.

Connect the serial adapter to the serial cable. Make sure the slide switch is in DCE position if straight cable is used and DTE position is NULL modem cable is used. For most of the cases, LM048 works in DCE position.
Start the LM149 Software. Select correct COM port and  factory serial settings <19200 8 N 1, flow : disabled>. Read settings from the LM048 Adapter. If settings are not read successfully, change the slide switch and try again.


Go to the Pairing Window on LM149 Software and press Pair Device button. It will pop up message “Connect Device 2 to COM 1 and Press OK”. Connect the other adapter to Serial Port and Press OK.


You will get a message “Connect Device 1 to COM 1 and Press OK”. Connect the original adapter to Serial Port and Press OK. At this point, the LM149 would read the Bluetooth Address and Name of both adapters.


You will get message “Pairing completed successfully” if above steps are OK. Press OK. Pairing Procedure is done.


Go to Local Device settings and check Device Address and Remote Address Box. Bonded address should be different from the device address.


If pairing procedure fails, please redo the pairing procedure from the step 1.

Configuring User Settings (Optional)

After pairing the adapters user may want to optionally configure both adapters to specific settings.

It is important to note that since the 2 adapters are now paired to each other, if you power up both adapters at the same time, they will auto-connect to each other. Therefore it is important that the adapters are not powered on at the same time when configuring user specific settings.

The below procedure assumes user wants to change the baud rate to 9600 bps once the adapters are paired. But user can also change any other settings

Note: Please don’t change the role and auto connect settings as this may cause issues with auto-connection.

Connect the 1st Adapter to the serial port. Make sure the 2nd adapter is powered off

Open LM149 Software and Read settings. Change baud rate to 9600 and Save Settings. The below screenshot shows the important settings on the master adapter


Disconnect Adapter 1 and power it off. Connect Adapter 2 and power it on. Press Reinitialise button on the LM149 Software. Change the baud rate to 9600 bps and Save Settings. The below screenshot shows the important settings on the slave adapter.


Once the master and slave adapter are configured to user specific settings, they are ready to use. The adapter retain their settings until user change the settings or factory reset the adapter.