Controlling Glideforce w/feedback (6") and JRK G2 21v3 CLI

I am stumbling over the protocol for using the JRK and these two items (Glideforce w/feedback (6") and JRK G3 21 v3) together.

How to move in either direction and any speed from any stopped point?

It works of course if I enter in the target (if it’s extended) to 4096 to retract it. And if retract, I enter 1448 to extend. That’s where my success ends.

How to move in either direction and any speed from any stopped point? With USB control, Is it 0-4096 or -600 / 600. Or 1448 to 2648?

APPLICATION: Trying to operate a large syringe. Constantly moving in one direction and only the opposite to reset. All moves must be relative to the last position. I see a target-relative but no real docs or examples and I’m hoping for a CLI example. Will gladly hire someone!

Please excuse my lack of prowess with your products and protocol. I’m new to your products. Does my question above make sense? I’m trying to do one simple thing over and over.

The --target-relative NUM command will read the current target from the Jrk, add the specified value to it, and send that as the new target. For example, if the current target is 2048 and you send --target-relative -100 the new target will be 1948.

What that target value means to the Jrk depends on what mode you are using it in. It sounds like you are intending to use the potentiometer feedback from the actuator for closed-loop position control, but it is not clear if you have successfully set up the feedback to work with the Jrk yet. If not, I recommend doing that and testing with the Jrk G2 Configuration Utility first. I recommend following the suggestions in the “Setting up analog feedback” section of the Jrk G2 user’s guide. We also have a pre-configured settings file for using those actuators with the Jrk G2 21v3. You can find it on the “Resources” tab of the actuator’s product page. You can use the “Open settings file” option within the Jrk G2 Configuration Utility then click the “Apply settings” button to load those settings onto your Jrk.

When that is set up, you should be able to control the position of the actuator with --target or --target-relative. Those commands don’t allow control of the speed directly, so you might want to use --max-duty-cycle NUM with an argument between 1 and 600 or --force-duty-cycle-target NUM with an argument between -600 and 600 to do that.


Thank you Brandon, but I’m entirely using OSX and shell scripts, cli commands. No ‘utility’ for osx like you have with the TIC.

This is why struggle. To be clear, I can move the actuator with the two sample commands. But it’s the concept…

  1. Why set a target? What does this mean? I get that with closed loop, (I’m assuming ‘w/feedback’ device provides the JRK) can use target instead of speed.

  2. But do you set target, then stop and then run - etc?

  3. Why will 1448 send it completely extended and 2448 will completely retract but any value to go in opposite direction must wait for shaft to hit it’s max limit each end.

  4. I can stop and run, but only after setting target and beginning run.

  5. So, with this specific device and board, is there a procedure you can offer, some commands to help understand the concept of simply doing the application I note.

I guess what I’m asking sir, is since you sell the device and board, and I want to buy 4 more sets, I’m struggling, not being on a windows and only linux and osx.

I would very much appreciate it my friend.

You can find the Jrk G2 Software for macOS download and installation instructions in the “Installing macOS software” section of the Jrk G2 user’s guide. Likewise, you can find the Linux download in the “Installing Linux software” section.

As I mentioned in my previous post, what the target value means to the Jrk and how it will respond to it depends on what mode you have it configured for. The target is used to specify a position when the Jrk is in analog feedback mode; when you are not using feedback or using frequency feedback, it specifies the desired duty cycle or speed, respectively.

I suggest reading through more of the user’s guide to get a better sense of what mode you should be using for your application or how you can control it to get the desired behavior.

Great thanks. I loaded settings via command line interface using --settings and used the file on the product page for the linear actuator.

Tadaa. Positional control.

I’m going to publish my shell script which does some great demos of steppers, and linear. I think other people new to your platform like myself might appreciate. Great I can buy 4 more.

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