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CAN-GC6 CANBUS Servo Controller


4 channel servo controller with GCA137 support for polarisation.

By Rob Versluis & Peter Giling


  • Position events.
  • Optional external switch position sensors.
  • GCA137 support for polarisation
  • Interactive comfortable setup and merg CBUS FLiM compatible.
  • Compatible 12VDC merg CBUS connector. (J3)
  • Opto-isolation for feed-back switches.
  • Individual direction-speed selection.
  • 'Bouncing' option.
  • Smooth running motor due to high resolution stepping.

The final board

Profesional boards are available.

LEDs, Jumpers & Connectors

2.3 Component side.

LED Function Aspect Color
L1 CAN activity Random Red
L2 FLiM learning mode (PB1) 1Hz Yellow
L3 CPU is running Continuous Green
L4 Servo busy 2.5Hz Red

Jumper Function
JP1 120 Ohm line termination¹

¹) A CAN bus must be terminated on both ends to get 60 Ohm.

Connector Function remark
J1, J2 CAN and 12V power only needed if used in CAN-GC system
J3 'MERG' CBUS and 12V power only needed if used in MERG Cbus system
S1..S4 Servo 1…4
F1..F4 External switch position feedback (2 inputs for each switch)
ICSP1 In-circuit serial programming
GCA137 Piggyback board connection for polarization

Connection Servo's

Most servo's come with a connector which will fit on Servo 1..4 connector on the CAN-GC6.
The signal line (useally orange ) should be at the edge of the board.

Mounting options for servo motor

A nice mounting support is available from GCA.
Sideways or in line movement is possible
The set contains all that is needed, incl. servomotor
see GCA servo support ServoSet

Connection limit switches

If you are not planning to use this option, F1..F4, U4 and U5 can be omitted.

F1..F4 are made for connection of limit switches, to feed-back that turnout is really on its desired position.
Switch should be on when position is OK

Connection should be made according this table :

Connector Turnout# position Connections
F1 1 straight C + S (1
F1 1 round C + R
F2 2 straight C + S
F2 2 round C + R
F3 3 straight C + S
F3 3 round C + R
F4 4 straight C + S
F4 4 round C + R

1) C = common, S = straight, R = round / turnout

See also here: Hardware feed-back

PSK header connectors

Some users seem to know better, and solder wires directly to the pins or the pc-board.!
That is totally unacceptable !!
Wires will easily break off, and cause a lot of damage in many cases.
So use connectors !!!!!
In order to ease making these cables, it is also possible to buy the necessary tool, to create the PSK cables.
The best wire to be used with PSK connectors is 0,25 mm².
This special plier is available for net price of € 20,00 if ordered together with complete kits. crimpzange.jpg
Just ask peter.


Servo sliders

L Left position
R Right position
SpL Speed left
SpR Speed right

The labels "L" and "R" are also test buttons. (7046+)

Polarization Relay

This options flips the polarization relay.

External sensor

Use the external sensor input for this servo instead of the generated event after reaching the wanted position.


Bounce the servo slightly after reaching the end position.


The Event Nr. to use for reporting that the servo is in position.


Shows the Rocrail object ID which is linked to this servo.

Short events

Ignore the event node number and compare the event number only.

Long events

For long events the BUS variable on the interface tab of sensors, switches and other objects is used to address the module its node number.
The address variable is equal to the one used with short events.


"Start of Day"
The servo positions will be reported at SoD event.

Node Nr.

Only for use with long events.

Save position

The servo positions will be saved in EEPROM after a Power Off message on CAN BUS.

Switch Setup

Single Gate

The switch interface option Single Gate must be set.

Hardware feed-back

CAN-GC6 is also provided with connections (F1..4) for hardware feed-back.
This is an extra option, to install a switch at both end positions of the turnout frog.
This drawing explains how to connect it.

Another possibility is the shared use of the circuit of the frog polarization. For this purpose, the frog is connected with the common terminal C = pin 2 and the two track polarities are connected with S = pin 1 and R = pin 3. In this case, the supply of the frog should not be linked over an occupancy sensor, because the current consumption of the optocouplers would simulate an occupancy of the switch. It should be considered that this kind of circuit give a reversed logic for the voltage at the optocouplers. So it's necessary that the not with the frog connected track polarity should connect to the corresponding terminal S or R.
Turnout feedbeck with the frog polarization circuit


The schematics
The pcboard with parts positions
Bill of materials
Gerber files
N.B. Only complete ordered kits will be supported!

Development Tools

can-gc6-en.txt · Last modified: 2020/07/15 10:48 by phg