===== USB communications setup =====

**newRPL** devices can communicate with **newRPL Desktop** by connecting the calculator to the host with a USB cable. There's some additional steps needed on various operating systems in order to communicate with the calculator:

**Windows**

No additional steps needed, just plug it.

**Linux**

The current user (the user **newRPL Desktop** is running as) needs to have read/write permissions to USB devices.

  - Create a new group ''usbdevices'', then add the current user to that group;
  - create a file (as root) ''/etc/udev/rules.d/50-HIDDevices.rules'', containing the following lines<code>
  KERNEL=="hidraw*", SUBSYSTEM=="hidraw", MODE="0664", GROUP="usbdevices"
  SUBSYSTEM=="usb", ATTR{bInterfaceClass}=="03", MODE="0664", GROUP="usbdevices"
</code>This will indicate the system to assign the group ''usbdevices'' to all new HID devices, and permits read/write to members of that group;
  - finally, restart the system for the new permissions to take effect.

**freeBSD**

The current user (the user **newRPL Desktop** is running as) needs to have read/write permissions to USB devices.

  - Create a new group ''usbdevices'', then add the current user to that group;
  - create a file (as root) ''/etc/devfs.rules'', containing the following lines<code>
[localrules=5]
add path 'ugen*' mode 0660 group usbdevices
add path 'usb/*' mode 0660 group usbdevices
add path 'uhid*' mode 0660 group usbdevices
</code>
  - edit the file (as root) ''/etc/rc.conf'' and add this line at the end<code>
devfs_system_ruleset="localrules"</code>
  - finally, restart the system for the new permissions to take effect.