Extended-Joint Option for RC8/RC8A

Modified on Wed, 28 Sep 2022 at 04:33 PM


Extended-Joint Function

The extended-joint function allows you to control extra joints independently of robot joints through the standard interface of the robot controller (RC8 series).

The extended-joint support system is different from the conventional robot system in the following points.

  1. Robot controller which is equipped with a driver board suited to extended-joint motors to be connected.
  2. The robot controller and extended-joint motors are connected using extended-joint motor cables, motor conversion cables, encoder cables, and encoder backup batteries (all of these are options).
  3. Extended-joint motors (option) which are equipped with bus-line encoders. (6-axis robot: up to 2 motors. 4-axis robot: up to 4 motors. Motor type available)

Sample of components needed (controller on the image is an RC8)

Necessary Components

Encoder Hub

Part No.Note

Encoder Cable

Part No. LengthNote

Motor Cable

Part No.LengthNote

Encoder Backup battery

Part No.Note

Encoder Battery Cable

Part No.LengthNote

Servo Motor 

Review the full list of AC Servo Motors https://www.fa-manuals.denso-wave.com/en/usermanuals/005479/

PowerShaft SizeOptions
30W40mm(brake)(oil seal)
50W40mm(brake)(oil seal)
100W40mm and 60mm(brake)(oil seal)
200W60mm(brake)(oil seal)
400W60mm and 80mm(brake)(oil seal)
750W80mm and 100mm(brake)(oil seal)
1000W100mm(brake)(oil seal)

Driver Unit

Note: One driver powers 2 motors. 
Part No.Description
410010-6120Driver Unit (L/S)
410010-7150Driver Unit (L/SS)
410010-6140Driver Unit (S/S)
410010-7160Driver Unit (S/SS)
410010-6550Driver Unit (SS/SS)

Power rating of driver unit letter

Power SizeMotor
SS30W, 50W, 100W
S200W, 400W
L750W, 1000W


  • To power a 750W and a 400W motors you need to use a L/S driver unit.
  • To power a single 400W motor you need to use a S/SS driver unit.
  • To power two 100W motors you need to use a SS/SS driver unit.

NOTE: It is not possible to power 2 750W or 2 1000W motors with a single driver unit since there is no L/L model.

Optional Components

Encoder Junction Cable

Part No.LengthNote

Motor Junction Cable

Part No.LengthNote

How many extra joints can I have?

How to mount the encoder hub?

Note: The encoder hub has the capability of being mounted on top of the RC8 controller as the image shows.

Setup Example

The following example assumes that your RC8/RC8A controller was originally purchased with the Extended Axis function.

Step 1: Connect the Motor and Encoder (Robot side)

Motor power from the robot will connect as usual (For a

VS068 SLOT1, SLOT2, and SLOT3).

The encoder connector will go to the encoder hub port

labeled as “Robot”.

Step 2: Connect encoder root cable

Connect one end of the encoder into the controller and the other into the encoder hub.

Step 3: Connect extended axis encoder

Connect one end of the encoder junction cable to the

extended joint motor.

Connect one end of the encoder junction cable to the

encoder hub on the joint 7 slot.

Step 4: Enable extended axis on the RC8

  • Turn on the RC8 Controller
  • Login as Maintainer and access Motor Settings.

Step 5: Connect power cable for extended axis.

Plug the connector on the correct slot and side.
Plug the connector on the motor side.

Step 6: Connect Encoder Battery

Connect encoder battery.
Power ON RC8

Step 7: Check encoder signal

  • Turn ON the RC8 controller
  • Access Encoder Info page.

Step 8: Calibrate extended axis motor

  • Login as Maintainer
  • Access the CALSET page.

Step 9: Perform Auto Gain Tuning for extended Joint

Step 10: Done (Jogging the extended axis)

To Jog the extended axis we need to click on the top button of the screen and select ExJoint before we try

moving the axis.

To Jog the extended axis we need to click on the top button of the screen and select ExJoint before we try moving the axis.

To Jog the extended axis we need to click on the top button of the screen and select ExJoint before we try moving the axis.
Sub Main
 'Get Arm Group 2 involving both robot 
 'joints and extended‐joints.
 TakeArm 2 Keep = 0 

 'Move robot flange to P0 as well as
 'moving 7th and 8th extended‐joints to 
 'relative coordinates synchronously.

 Move P, P0 Ex ((7,30),(8,10)) 

 'Move robot flange to P1 as well as
 'moving 7th extended‐joint to absolute 
 'coordinates synchronously.

 Move P, P1 ExA ((7,30))       
End Sub

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