Jrk 21v3 and Micro Maestro

HI, I am trying to control a Invenscience i00600 Torxis Servo (w/ Jrk21v3) with a Micro Maestro. I seem to be having trouble getting the motor to respond to commands via the Maestro Control center. I would like to be able to control 2 of these Servo motors via the Maestro (USB COM port). I have looked at the connection diagrams, but I still cannot get the motors to run. I can control them fine using just the Jrk configuration utility, but when I switch to the Maestro set-up my connections must be off. How can I make this work?

To control the Torxis servo using the Jrk Configuration Utility, you must have taken it apart and changed the Input Mode setting on the jrk inside. Did you remember to revert it back to the original settings before trying to control it with your Maestro?


Yes, I did take it apart and plug in the USB cable directly to the Jrk. I have changed all the settings back on the Jrk to factory default, but I still cannot get it to work with the Maestro.

How exactly did you revert the jrk’s settings? What buttons did you click?


I used the “Reset to default settings” under “File”.

Unfortunately, by doing that, you wiped out all the configuration settings loaded onto the jrk by Invenscience to make the torxis work. Did you happen to save a settings file before modifying the settings?


Whoops. No, I did not. The Torxis works with the Jrk just fine, just not when I plug it into the Maestro. I guess what I’m getting at is: If I want to plug the Torxis into the Maestro to control it, how should I have it connected? And how does the Jrk need to be configured (input mode/feedback/etc.)?


In general, to a wire jrk to be controlled by a Maestro, you only need to connect the GNDs together and you need to connect one Maestro channel’s signal line to the RX line of the jrk. The Torxis servo makes this easy to do because they bring GND (the black wire) and RX (the white wire) to an external cable.

Several configuration parameters on the jrk need to be set. Input Mode should be set to “Pulse Width”. The input scaling should be set so that the Maestro’s shortest pulse corresponds to a Target of 0 and the Maestro’s longest pulse corresponds to 4095. Feedback Mode should be set to “Analog”. The feedback scaling should be set so that the Scaled Feedback variable goes from 0 to 4095 as the Torxis moves through its full range of motion. You will need to set PID coefficients. If the feedback doesn’t work as expected, you may need to either invert the motor direction or invert the feedback direction (depending on your definition of forward). There are other settings that you might want to set too. The “Setting up your System” section of the jrk user’s guide has more information, especially with regards to choosing good PID values. While configuring the jrk you should take precautions to avoid breaking the Torxis servo (e.g. set a max duty cycle limit in the jrk and/or lower the power supply voltage).

I’m guessing that you like to learn these kinds of things, but if you don’t then I would recommend emailing Invenscience with your servo’s model number and asking them to give you the latest jrk settings file they are using for that model.