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# 3.3. Installing macOS software

To install the configuration software for the Jrk G2 on a computer running macOS, follow these steps:

3. After the installation has completed, plug the Jrk into your computer via USB.
4. In your Applications folder, look for “Pololu Jrk G2”. Double-click on “Pololu Jrk G2” to start the configuration utility.
5. In the upper left corner of the window, where it says “Connected to:”, make sure that it shows something like “18v19 #01234567”. This indicates the version and serial number of the Jrk G2 that the software has connected to. If it says “Not connected”, see the troubleshooting section below.

This Jrk G2 software consists of two programs:

• The Jrk G2 Configuration Utility (jrk2gui) is a graphical user interface (GUI) for configuring the Jrk G2 and viewing its status. You can run it by clicking on “Pololu Jrk G2” in the Applications folder, or you can open a terminal and type jrk2gui to run it.
• The Jrk G2 Command-line Utility (jrk2cmd) is a command-line utility that can do most of what the GUI can do, and more. You can open a terminal and type jrk2cmd with no arguments to a see a summary of its options.

The source code for the software is available. The Jrk G2 does not require any driver installation on macOS.

#### Software installation troubleshooting for macOS

If you get the error “command not found” when you try to run jrk2cmd or jrk2gui, then you should try starting a new Terminal window. The installer adds a file named 99-pololu-jrk2 in the /etc/paths.d directory to make sure the software gets added to your PATH, but the change will not take effect until you open a new Terminal window.

The Jrk G2 software will not work on versions of macOS prior to 10.11.

#### USB troubleshooting for macOS

If the Jrk G2 software cannot connect to your Jrk after you plug it into the computer via USB, the tips here can help you troubleshoot the Jrk’s USB connection.

If you are using the Jrk G2 Configuration Utility, try opening the “Connected to:” drop-down box to see if there are any entries in the list. If there is an entry, try selecting it to connect to it.

Make sure you have a Jrk G2. The Jrk G2 software does not work with the older Jrk 21v3 or Jrk 12v12. If you have one of those products, you should refer to its user’s guide instead of this user’s guide.

Make sure you are using software that supports the Jrk G2. The original Jrk Configuration Utility does not work with the Jrk G2. The Jrk G2 controllers have new USB product IDs. Third-party software for the older Jrk 21v3 and Jrk 12v12 controllers might need to be updated, depending on how the software works. If you are a developer of such software, see Section 1.2.

If you have connected any electronic devices to your Jrk besides the USB cable, you should disconnect them.

You should look at the LEDs of the Jrk. If the LEDs are off, then the Jrk is probably not receiving power from the USB port. If the green LED is flashing very briefly once per second, then the Jrk is receiving power from USB, but it is not receiving any data. These issues can be caused by using a broken USB port, using a broken USB cable, or by using a USB charging cable that does not have data wires. Using a different USB port and a different USB cable, both of which are known to work with other devices, is a good thing to try. Also, if you are connecting the Jrk to your computer via a USB hub, try connecting it directly.

If the Jrk’s green LED is on all the time or flashing slowly, but you can’t connect to it in the software, then there might be something wrong with your computer. A good thing to try is to unplug the Jrk from USB, reboot your computer, and then plug it in again.

Another thing to try is to run dmesg right after plugging in the Jrk to see if there are any messages about it.

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