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Appendix B. Configuring electrical linking of dual control stations (under development).

V1.100 of the CL software has updated code for electrically linking dual pilot & co-pilot controls (stations). This feature is still under development....

The electrical linking operates by setting one of the flight control stations as the "Master" station and one as the "Slave". The master station continues with normal FFB and the slave station goes into a PID controlled position following mode in which it mimics the movement of the master station.

Which station is master and which is slave can be swapped at any time using joystick card buttons assigned for the task. For a pilot/co-pilot to take flight control at his/her controls when they are currently assigned as the slave station he/she must first toggle the master/slave button to make his/her controls active.

This is a limitation of the electrical linking method - if you can't live with this then it might be better to link your two control stations mechanically.

Which station is used to feed position to FS depends on the operation mode of the CL system.

When the CL system is operating in its original mode in which joystick card position data is used as the input to FS then regardless of which station is master it is the position of the pilot controls that the system adopts as the inputs to FS. When the co-pilot station is master the method relies on proper position following by the pilot station (as slave) to provide the position inputs to FS.  So trying to control the aircraft using the co-pilot station when it is assigned as the slave station will not have any effect on the aircraft.

When the CL system is in "potentiometer-less" mode then it is the position of the "master" station which is used to feed the FS controls via FSUIPC (using the motor encoder position data). So the station used to provide position input to FS will change as the master/slave toggle switch is operated to make one or other station the controlling station. 

The position following methods used for electrical linking are the same as are used by the system for Auto-Pilot position following.

TIP: before trying to set up dual control electrical linking confirm that AP position following is fully operational on your pilot station controls - this will save you time later!

Important Pre-requisites:

1. The pilot and co-pilot controls should be mechanically and electrically identical. A single set of PID position following settings will be used for both and so will NOT produce similar position following performance on mechanically different stations. This can give problems.
    
2. All BLDRV-12/24 driver cards should have the same firmware programming.
    
3. Each station should be set up and tested as a stand-alone system before setting up the electrical linking. This requires that each station has its own joystick card - although, once linking is active, ONLY the pilot card should be assigned in FS as the control input.
   
   NOTE for systems configured for "potentiometer-less" operation game-controller card position reporting is not required for the main axes on either station. See Appendix A for details.
    
4. Good Auto-Pilot position following behaviour should be confirmed on the pilot control station at least BEFORE setting up the electrical linking. This means the movement of the pilot controls during AP following should be smooth and of expected range.
    
5. A single "momentary" button on each station's joystick card should be reserved for the master/slave station swap/toggle function. Ideally these would be located on the control yokes for convenience of operation by the pilots.
   
   NOTE for systems configured for "potentiometer-less" operation the assigned toggle buttons should be on the single joystick card used for the trim inputs (either the pilot station "stick no" or alternative trim button stick number set in the Setup App).
    

Configuration Settings: Run the BFF Setup application and go to the elevator area - Tab 1 - Setup.

1. Under the COMS Settings set the Co_Pilot COM port number for the PICAXE AXE027 cable used to connect to the co-pilot station driver cards.
    
2. Set the Co-Pilot Joystick No, to the joystick card number for the co-pilot controls (click the List Sticks button to identify the number - or run the BFF Driver Test application and check the stick number there).
   
   In the case of systems configured for "Potentiometer-Less" operation set the Co-Pilot Joystick No = -1 to enable the electrical linking.
    
3. Set the upper Toggle But number to the button on the pilot station joystick card which will be used as the master/slave toggle button. And set the lower Toggle But to the button number on the co-pilot joystick card used for the same purpose.
   
   In the case of systems configured for "Potentiometer-Less" operation both buttons will be assumed as being on the "Pilot" joystick card - ie usually the card used for trim inputs etc.
    
4. SAVE the settings.
    
5. Make sure that only the Pilot station joystick card is assigned in FS for the main control inputs (but not for "Pot-less" configurations).
    

This configures the system for electrically linked dual stations. When the system starts and the loading is engaged one of the stations will be in master mode and the other in slave (position following) mode. Clicking either of the master/slave toggle buttons will swap the master and slave stations.

Check that the position following is active and the slave controls follow the master's movements smoothly. Check that the control inputs to FS are satisfactory and that the aircraft can be flown satisfactorily from the co-pilot station.

The position following behaviour is determined by the PID values in the background process settings. If necessary the overall strength of the position following forces can be increased by altering the programming of the 20X2 chips on the cards. By default the position following forces are capped to protect the system.

When AP following mode becomes active BOTH stations should follow the control actions of the AP and displacement of either set of controls should cause the AP to disengage - this will set the displaced controls as the new Master station.

(NOTE: In v1.285 of the BFF Background Process the direction of movement of the slave station can be reversed using the background process setting Line 74: Slave movement invert in the Setup Application.)

PLEASE NOTE: this is developmental, it is likely that additional tuning is required to the coding - so watch out for bugs or other strange behaviours.

Still to be implemented:   

• Provision for 2nd PICAXE cable on co-pilot station (to match dual cable capability on pilot station)
   
• Visual display of ping status of co-pilot station cards on the CL software window (although the data is written to the BFF_Pry.log file as usual).  -- NOW implemented in V1.111 --

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