Bantam Tools Blog

The Othermill and Mac OS X 10.11 El Capitan

Posted by Owen Smithyman on Oct 12, 2015 12:09:00 PM
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Update (1/27/2016): The Otherplan incompatibility with El Capitan has been resolved. Apple has released Mac OS 10.11.3, which addresses the issues that were causing problems with Otherplan. We have released Otherplan 0.14.7, which integrates with the fixes Apple made. This officially resolves the issue with El Capitan. For a working setup, make sure you have Mac OS X 10.11.3 or newer, and Otherplan 0.14.7 or newer.

Update (10/15/2015): We have just released Otherplan 0.14.6, which addresses the USB communications issues described below. Open Otherplan to update, or download here.

The release of Mac OS X El Capitan has caused a number of problems for Otherplan users. We have investigated these problems and want to share some details about what’s going on.

In short, OS X El Capitan has introduced USB communication bugs that make it difficult to communicate with the Othermill and other USB devices. If possible, we recommend that Othermill users wait to upgrade to El Capitan until these bugs are resolved. We will be releasing an Otherplan update shortly that includes workarounds for people using El Capitan.

Here are the technical details:

Otherplan communicates with the Othermill using a USB serial protocol. Much of the code that makes this possible is not contained within Otherplan, but within the operating system kernel itself.

Apple rewrote large portions of their USB communications code for El Capitan. The changes they made were not intended to change the OS’s behavior, and OS X applications like Otherplan were expected to keep working without modification. Unfortunately, this has not been the case, and the public El Capitan release contains a number of bugs that prevent Otherplan and many other apps from working properly. (Other affected products include Arduino, RoboPaint, serial port libraries, and many audio devices.

  1. The operating system sends notifications to Otherplan when an Othermill is connected or disconnected. However, in El Capitan, these notifications are missing information that Otherplan needs in order to find the newly connected mill and establish communications with it.
  2. Once Otherplan has detected an Othermill, it is sometimes unable to open a connection to it because the operating system wrongly believes that the connection is already open.
  3. When a connection is opened, the first attempted transmission to the Othermill always fails silently, even though the operating system reports that it succeeded. We’re still testing to determine whether this problem only occurs right after the connection is opened, or if it can occur at other times as well.
  4. When jogging V1 Othermills by holding down the arrow buttons, communications between Otherplan and the mill can temporarily break down, causing the jog-stop character to be delayed by up to a second.

As soon as we found out about these issues, they immediately became our team’s highest priority. We have been working hard to develop workarounds in the OS X version of Otherplan. (The issue affects both the OS X version of Otherplan and the Otherplan Public Beta, but we are prioritizing a fix for the original version first to help our long-time Mac users access the full functionality they need as quickly as possible.)

We’ve also filed bugs with Apple about the issue, and a number of users of other USB devices have done so as well. We are hopeful that a fix will be forthcoming in the next El Capitan release. In the meantime, we will be releasing our workarounds for El Capitan as soon as we have tested them and verified that they are robust.

We apologize for any problems this has caused, and will share more information on our blog as soon we receive it. If you have any questions, please contact our support team at

Topics: Software, Announcements, Otherplan, OS X