TH-2 Support                                                                                                  

    Last updated on:8-30-09

TH-2 Software Downloads


TH-2 Tandem Control Software - Tandem Rotor Helicopter

Tandem Helicopter Control Software

TH-2B005 software download (40 KB)  Download Software
TH-2B005 software release notes download (1 KB)   Download Release Notes


TH-2 VTOL Control Software - VTOL Aircraft

TH-2 VTOL/Tandem Control Software

VTOLA001 software download (40 KB) Download Software
VTOLA001 software release notes download (1 KB) Download Release Notes


TH-2 UMIX Control Software - Universal 5 x 8 Mixer  NEW

UMIXA001 software download (46 KB)   NEW Download Software
UMIXA001 software release notes download (1 KB)   NEW Download Release Notes
UMIXA001 software features download(6 KB)   NEW Download Features


TH-2 RC-Heli Review  

TH-2 Online Users Guide

TH-2 Functional Overview
TH-2 Software Installation
TH-2 Software Loading
TH-2 Software Specifications...
Inputs/Outputs Description

Power Requirements
Servo Drive Capability
Receiver/Gyro Compatibility
Special Precautions
TH-2  Inputs Connections
TH-2  Servo Connections
Run Mode / Trouble Shooting
Preflight Checklist
TH-2  General Information
TH-2 Hardware Block Diagram

TH-2 Functional Overview

Once the TH-2 is programmed and setup with your PC, there is no longer any need to have a PC at your flying field etc.
All changes can be done with your transmitter.  The only things that may need adjusting are the input gains with can be
done with the transmitter ATVs.   Also,  the DCP gain can be changed as well since it is a transmitter pmix.

For example, setting up for our Twinn Rexx tandem requires you to download a constants file and then just load it into the TH-2 using
your PC.  The servo centering then needs to be updated for each servo which is a back and forth exercise that takes about 15 minutes.

The TH-2 synchronizes to your transmitters frame rate using channel 6.  It operates and will update all the servo outputs at the
same rate as your transmitter does.  This is considered real time.  There is nothing faster than this or "instantaneous".


TH-2 Software Installation

  1. The Tech Link software must already be installed for this installation to work properly.
    NOTE: The TH-2 software will be installed at the path "c:\Program Files\Tech Link V1.1"
    if you changed that location you must manually copy over the TH-2 software.
    See the software release notes for more information.
  2. Create a temporary folder and download the TH-2 software into it.
  3. Run the setup program by double clicking on it and follow the instructions on the screen.
  Directory screen shot after the installation


Using the Tech Link Software

TH-2 Software Loading

  1. Plug the TH-2 (or just the FCPU-1 board) into a USB port.  The USB cable must be plugged into an un-powered TH-2 to operate. 
    Power is supplied by the cable.  No damage will occur if you forget to remove battery power first.  It just won't work.
  2. Run Tech Link
  3. Click Load on the Program menu.  Browse the TH-2 directory and select the ".hex" file.
    Don't forget to load the constants if you haven't already.  This is done by clicking Load
    on the Constants menu. Browse the TH-2 directory and select the desired ".cst" file.


TH-2 Software Specifications

Tandem Helicopter Control Software

VTOL/Tandem Control Software


Inputs/Outputs Description

The following table describes the purpose of the TH-2 inputs/outputs:

  Name Type Description  
Aileron input Aileron input from Rx or gyro
Elevator input Elevator input from Rx or gyro
Rudder input Rudder input from Rx or gyro
CH5 input CH5 input from Rx or gyro
  Pitch input Pitch input from Rx (Note: A gyro must not be used on this input)  
GP I/O I/O General purpose I/O ports (4) for future use
Serial / I/O J3 I/O Serial port or (2) general purpose I/O ports for future use
Factory/Reset J2 I/O Factory use port and external reset input for a watchdog timer
Main connector J1 I/O & Power Main connector from the computer board to application boards
USB I/O USB "Mini-B" type jack for connection to a PC
Front servo outputs Front servo outputs Ep, A, E, P   (Note: Ep = E prime)
Rear servo outputs Rear servo outputs Ep, A, E, P   (Note: Ep = E prime)
Secondary power input Additional power input needed in some cases depending on size and quantity of servos.  See the servo drive chart.   Note: Any unused headers can be used to supply power using connectors as well.

Inputs/Outputs Diagram


TH-2 GP Board Close-up


TH-2 Micro Board Close-up



Power Requirements

The TH-2 requires a 5 volt power source. It must be maintained between 4.9 and 5.1 volts. 

Do not exceed 5.2 volts since it can damage the unit.  

We recommend using a 5V BEC with a battery large enough supply the power needed.

Care must be used when choosing the power source since it must be capable of driving the intended load.  The TH-2 itself uses very
little power (not much more than an LED) so you need to determine how much current is required by all of the components in your model. 
This would include components such as:

  • Receiver
  • Gyros
  • Servos
  • Accessories

Many of the Electronic Speed Controllers (ESC) on the market have a BEC which can only supply 1 amp of current.  This would be insufficient in a
model setup that has a receiver, 6 micro servos, and 2 gyros.  A BEC with 3 amp capability would be needed.

For large or digital servos you will need to use extender boards or similar,  which allow you to route power directly to the servos bypassing the TH-2. 
The TH-2 only drives the servo input signals which are low power.

Servo Drive Capability

The TH-2 is designed to drive up to six (6) micro servos (HS-50, S3108, etc.) with just the primary power input.  Any more than this
requires the secondary power input or the use of the extender boards.  These limitations are due to the current carrying capacity of
the connectors.  Using the secondary power inputs (even if not required) provides redundancy and is recommended for safety.
The Servo Drive Table below summarizes the possible combinations of different servo counts and sizes with the required power inputs. 

                                                                                      Servo Drive Table

 Servo Type  Max Servos  Primary Power  Secondary Power (4)  Extender
Micro 6 Yes Optional Optional
Micro (3) 8 Yes Yes (1) Optional
Mini (3) 8 Yes Yes (1) Optional
Large/Digital (3) 8 Yes N/A (2) Yes
Notes:  1: Secondary power is not required when extender boards are used.
            2:  N/A means Not Applicable.
            3:  Only the TH-2 GP model has 8 outputs.
            4:  Any unused header power pins can be used as secondary power inputs.


Receiver/Gyro Compatibility

The TH-2 requires a low jitter receiver/gyro to operate properly. The receiver/gyro should have a jitter level of about 1 to 2 microseconds or less.
The TH-2 measures the pulse widths from the receiver/gyro outputs and then performs 32 bit calculations on these measurements to perform
the mixing.  Any receiver or gyro jitter error adds and subtracts, with mixing,  which in some cases doubles or halves the error.
A typical servo has a deadband of about 8 to 10 microseconds, any jitter above the deadband will cause the servo to hunt and twitch.
The TH-2 will work with either "Heading Hold" or standard gyros. We recommend using the Futaba GY240  gyro since it is a high quality unit,
works well and has low jitter.  Other units on the market may perform just as well, we just have not tested them yet. 

The GY401 gyro has been tested and works fine.  The gyro should be set to work in "analog" servo mode.
The FS8 Copilot system has been tested and works fine.

DX7 and DX6 radios have been tested and work fine.  They output the data just as a PPM receiver does with a 22ms frame rate.

Note: Some PCM receivers output servo data "non-sequentially" and may not completely work with the TH-2.

Update: 2/27/07 - The new software version TH-2B005 has been updated to work with Futaba PCM radios.
                          It may work with JR PCM  but is untested at this point.

Special Precautions

  •  Caution:  The TH-2 does not have any failsafe features.  It operates as a slave device driven by the receiver.  Any glitch or interference passed from
     the receiver to the TH-2 will cause the servos to operate erratically.  The TH-2 does provide clamping to the servo outputs to prevent damage.
  •  Caution:   It is important that the TH-2 is connected properly before the power (battery) is connected. Failure to so do may damage the TH-2 and
     whatever it is connected to at the time.  The TH-2 supports most radios such as Futaba, JR, Hitec and others without modifications.
  •  Caution:  Power should be removed or switched off when making any kind of connections to the TH-2.  This includes the USB.
  •  Caution:  The TH-2 assumes a center positive power pin for the connectors.  Some radio equipment such as Airtronics, uses a center negative
     power  pin.  The appropriate connector adapters must be used in this case.

TH-2  Inputs Connections

The TH-2 has 5 inputs that come from the receiver.  Optionally, 4 of these inputs (all but the pitch channel) can be connected to the receiver through a gyro.

  • Aileron input is a 3 pin connector shell the plugs directly into the receiver's Aileron output or optional gyro.
    The gyro if used, plugs directly into the receiver's Aileron output.
  • Elevator input is a single pin connector, color coded GREEN, that plugs into the receiver or optional gyro. 
    The gyro if used, plugs directly
    into the receiver's Elevator output.
  • Rudder input is a single pin connector, color coded BLUE, that plugs into the receiver or optional gyro. 
    The gyro if used, plugs directly
    into the receiver's Rudder output.
  • CH5 input is a single pin connector, color coded BLACK, that plugs into the receiver or optional gyro. 
    The gyro if used, plugs directly
    into the receiver's CH5 output.
  • Pitch input is a single pin connector, color coded YELLOW, that plugs into the receiver.  
    NOTE: A gyro must not be used on this input.


TH-2  Servo Connections

The TH-2 has 6 or 8 servo outputs depending on which application board you have.
The servo connectors can be plugged in directly to the servo output headers.  The servo signal wires must be facing the the labels A, E, P or Ep.
Connecting the servo connector on backwards will not harm anything.  The servo just won't operate.

When using extender boards and long signal wires, it may be necessary to use ferrite rings on the signal wires to prevent glitching. 
This will depend on your particular installation.

Run Mode / Trouble Shooting

Following power-up, the  TH-2 will enter Run mode if the USB is not connected and a valid software application was loaded.
The red Status LED will blink about twice a second indicating that the TH-2 is operational.  If the Status LED fails to blink
(LED stuck on or stuck off) this indicates a problem exists.  Below is a list of things to check that may be the cause:

  • Check that the power is connected and the battery is charged.
  • Check that transmitter is operating properly.
  • Check that receiver is operating properly.
  • Check that the receiver/gyro inputs are connected properly.

Preflight Checklist

This checklist at a minimum should be performed before each flight of the model:

  • Inspect the model for flightworthiness.
  • Perform a radio range check before attempting to fly the model.
  • Check that the TH-2 is operational (Status LED blinking).
  • Check the controls.
  • Happy flying

TH-2  General Information     

  • The USB cable must be plugged into an un-powered TH-2 to operate.  Power is supplied by the cable. 
    No damage will occur if you forget to remove power first.  It just won't work.
  • TX type, servo type, servo layout, and servo arm position will determine the servo reversing settings needed in
    the TX and TH-2. 
  • The TH-2 synchronizes with the pitch channel (CH-6 on most radios) and expects it to be the last pulse
    (that it "sees") in the data frame sent by the transmitter.  Also, A gyro should not be used on this channel.
     It wouldn't make sense anyhow.
  • The gain settings also allow you to balance the amount of servo travel from the contributing channels and
    prevents clamping.  The TH-2 is set to clamp at 0.90 ms min. and 2.10 ms max. to prevent servo damage
    in the event of interference.

  • Error notification - An error condition is indicated when:

    USB connected USB disconnected and application running
    Yellow and green LED's are ON Yellow and green LED's are blinking alternately

    An non-error condition is indicated when:

    USB connected USB disconnected and application running
    Green LED is ON only Yellow and green LED's are OFF


  • Error handling and reporting - Tech Link displays the current error status by clicking on View Error on the Tools
    menu. The error status is set upon each power up cycle only when the USB cable is disconnected.  This
    means you must apply power to the unit without having the USB cable attached to "set" the error code.  You then
    must connect the unit to the USB cable and use Tech Link to display the current error code.


TH-2 Hardware Block Diagram 








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