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Showing posts with label LGB 55040 Additional function board. Show all posts
Showing posts with label LGB 55040 Additional function board. Show all posts

Saturday 22 October 2022

LGB 55040 Additional function board:


Other Blog posts for further details and information:






As the PIKO/Massoth DCC systems are capable of sending both Parallel and Serial commands, either method can used to activate  Relay 1 and Relay 2.



Designed and constructed test rigs, to test and understand how to configure the LGB 55021 decoder and the LGB 55040 Additional function board, for correct operation to use either Serial or Parallel functions from the Navigator handset. 

The Navigator also has the ability to store individual Loco definitions as defined by the User, therefore a configuration can be setup that is tailored and unique to a particular Loco and has no bearing on the operation of other Loco's.

The LGB 55021 (V2.50) decoder  has the ability to recognise and differentiate between Parallel and Serial commands, and will act accordingly as per how the relevant CV's are configured.

Brief description of LGB serial pulse chain solution.

One of the earlier forms control on the LGB MTS system was the MTS mouse which had a button that activated a function on the loco.


Within a short space of time the activation of one function on a loco was limiting, and more choice was needed to activate more than one function.

With the MTS mouse there was only one function button, how to control function 2 and function 3 and 4 etc.?

Having only one function button, that could only control one function, LGB devised the serial pulse chain solution, whereby pushing the function button multiple times, would activate the higher function outputs.

To send function button F3 for instance, press the function button on the mouse three times. the MTS central station sends out the 'packet' for F1 three times, the decoder counts the number of F1 packets it receives and in this case turns on the assigned F3 output.

Note, that any decoder that cannot recognise serial pulse chains, will decode the signal as three F1 ‘packets’ and not as one F3 ‘packet’.

Accessing F2 and F3 the process worked reasonably well, although it became cumbersome with the higher functions, take F8 for example where the mouse button has to be pressed eight times, which became unreliable.

LGB eventually introduced what they called "parallel" operation which is the normal for DCC operation, each function has its own unique DCC packet and the function is activated as soon as the packet signal is received.

Within the RCN DCC standard, it is designed for assigning different coded 'packets' for each function output.

When a function key such as 1 was pressed, the central station would send the appropriate 'packet' signal for the assigned F1 output, the decoder would detect it and turn on the F1 output of the decoder, same for F1 to F28 outputs. Each function output has a different 'packet' signal that is generated by the central station based on which function button was pushed.

LGB 55040 as supplied  setup and tested as per factory default, Relay Module connected to the F1 output on a LGB 55021 decoder, operating in either Serial or Parallel configuration to activate the 55040.


Configure CV 51 = 1 for default operation of the additional function board.

Using this configuration allows control via Function Keys 1 - 8, via Serial commands.

Press Function Key 1 for Relay 1 activate/deactivate.

Press Function Key 2 for Relay 2 activate/deactivate.

For Parallel operation. 

Single press of Function Key 1 to activate/deactivate Relay 1.

Double press of Function Key 1 to activate/deactivate Relay 2.


LGB 55021, CV 51, CV 52 and CV 53, refer to notes as for CV 51.

Serial Mode configuration for CV 51.
CV 51 = 1, meaning activation by Function Key 1 to operate Function Output 1.

Whilst in this configuration Function Keys F2 to F8 will be active and will operate the Function Output as described.

CV 51 = 9, meaning activation by Function Key 1 to operate Function Output 1.

Whilst in this configuration Function Keys F2 to F8 will be deactivated and therefore will not operate the Function Output as described.

CV 51 = 10, meaning activation by Function Key 2 to operate Function Output 1.

Whilst in this configuration all other Function Keys F1, F3 to F8 will be deactivated and therefore will not operate the Function Output as described.

CV 51 = 11, meaning activation by Function Key 3 to operate Function Output 1.

Whilst in this configuration all other Function Keys F1, F2, F4 to F8 will be deactivated and therefore will not operate the Function Output as described.

And so on up to CV 51 = 16, meaning activation by Function Key 8 to operate Function Output 1.

When in Parallel Mode the configuration for CV 51 takes on the following meaning.

CV 51 = 1, meaning activation by Function Key 1 to operate Function Output 1.

Whilst in this configuration Function Keys F2 to F8 are deactivated and will not operate the Function Output as described.

To access the device on Function Output 1, for activation of F1 button, single key press of Function Button 1, to either turn on or turn off the device.

To access the device on Function Output 1, for activation of the F2 button, double key press Function Button 1, to either turn on or turn off the device.





With the help of this Relay function board, two special function of the locomotive may be operated, bell, whistle, etc. can be operated from the Navigator Handset.

Up to four additional function boards, which enable up to eight special functions to be operated, can be fitted into one locomotive.

The additional functions can be activated via the Navigator handset. For each function select between four types of function available.

ON/OFF switch (for smoke unit, internal lighting etc.)

Momentary contacts with adjustable times (for bell, whistle etc.)

Flashing ON/OFF identical (flashing lights)

Flashing ON/OFF intermittent (blinking lights)

Connection of the three leads from LGB 55040 board to the LGB 55021 decoder,

White to Decoder Positive,

Red to F1 Function Output,

Black to Decoder Negative.


Further 55040 boards can be fitted to the pins that are adjacent to the leads. This operation can be repeated with up to four 55040 boards so that a maximum of eight functions can be activated.

Allocating the function number, the mode of operation and the timer period, via the block of eight DIP switches.


With a little ingenuity, can use the output from the Relay to trigger this module as in the picture below, which can then switch power to an external device.

By setting the  LGB 55040 to operate in Momentary mode with a Function key, can trigger the module to latch ON, pressing the Function key again will unlatch and turn the power source OFF. 





Operating a Massoth lighting board, using a Bistable Latch Switch, input voltage from  Bridge Rectifier to convert the DCC voltage to DC.
Further reference to the module used can be found in this Blog Posting on Relay's and alternative devices, near the bottom of the post, Bistable Latch Switch.







Connected to a 2 Channel 5V Relay Module, Navigator handset configured for Serial operation of the  F1 Function Output.

Function Key 1 to activate/deactivate Relay 1, Function Key 2 to activate/deactivate Relay 2, the activated  Relay contacts from the LGB 55040 provide the NEG Trigger to activate the Dual Relay Module.




Single Relay Module, and Modified Servo Tester, operated with Parallel Mode from the Navigator Handset.

For Parallel operation,

Single press of Function Key 1 to activate/deactivate Relay 1.

Double press of Function Key 1 to activate/deactivate Relay 2.



Massoth L Decoder, Single Relay Module, and Modified Servo Tester, operated with Serial Mode from the Navigator Handset.

Can be operated by either with method one:

Single press of Function Key 1 to activate/deactivate Relay 1 on the LGB 55040.

Double press of Function Key 1 to activate/deactivate Relay 2 on the LGB 55040 .

Or via method two:

Press Function Key 1 for Relay 1 activate/deactivate on the LGB 55040.

Press Function Key 2 for Relay 2 activate/deactivate on the LGB 55040.




Massoth L Decoder to a Dual Relay Module.

Massoth CV 49 = 9
Serial & Parallel with Fast Pulse A1.

Function Key 1 to activate/deactivate Relay 1.

Function Key 2 to activate/deactivate Relay 2.




LGB 55040 Additional function board, setup for Momentary action to activate Next/Vol-, Prev/Vol+, additional LGB 55021 F2 Output, via a modified Optocoupler Module, configured to operate Momentary on Function Key F3 for Play, all operating in Parallel Function Mode. 

For Parallel operation, single press of Function Key 1 to activate/deactivate Relay 1 for Next/Vol-.

Double press of Function Key 1 to activate/deactivate Relay 2 for Prev/Vol+.