How to send commands to change the PID parameters with Jrk G2 21v3

In our own labview software ,we send commands to set target and get the feedback successfully,via a virtual com port.
We also can change the PID parameters by the Pololu Jrk Configuration Utility.
But we want to know , how to send the commands to edit the PID parameters.(Proportional Coefficient, Integral Coefficient and Derivative Coefficient )
What are command bytes of the PID parameters?
Please help!
Thank you!


The PID coefficients are stored in the Jrk G2’s EEPROM, which can only be changed via the native USB interface. However, you can use the “Set RAM settings” command to temporarily override the copy of these settings stored in RAM. You can find more information about this command (including an example for changing the proportional coefficient) in the “Set RAM settings” heading of the Command reference section of the Jrk G2 user’s guide.

As mentioned, please note that the effect of this command is temporary; the settings will be reloaded from EEPROM whenever there is a full microcontroller reset and whenever it receives a “Reinitialize” command.

You will also need to refer to the “Serial command encoding” section to learn how this command is encoded in the Jrk’s serial protocol.


Thank you for your reply.
New problem, from USB SDK MASTER we can get Jrk.dll and the UsbWrapper.dll files, I want to use them in the Labview software,but we get an error message “System.NullReferenceException”.
Can you tell me how to use them in Labview software correctly?

Our USB SDK does not currently support the newer Jrk G2 controllers. I do not have a lot of experience with LabVIEW, but I suspect it might be easiest for you to use the Jrk’s USB virtual serial port. You might also consider using the Jrk G2 Command-line Utility (jrk2cmd).


Yes.I used the Jrk’s USB virtual serial port,but after running sometimes ,the communication broken, then I must restart my PC or reinstall the driver.
I confused that the virtual serial port can work in my personal computer,but cann’t work properly in our test bench.
Out test bench except the Jrk controller,there are some other instrument, like PCI DATA acquisition card,Serial Resistance Meter,Laser marking machine…
Is that a problem?

What version of Windows are you using?

When you say that you have to restart the computer or reinstall the driver, do you mean that sometimes restarting the computer does not fix the problem, so you have to reinstall the driver, or do you mean that doing either one will fix the problem?

What happens when the communication stops working (e.g. do you get any errors and does the controller still show up in your Device Manager)? You might consider trying a USB cable with ferrite beads at both ends as well as a powered USB hub, in case the problem is noise related.