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This ROS package is a driver node for controlling the roboteq SDCx motor controllers.

Devices that have been used successfully

  • SDC2130

Setting up udev

We plug these in via a mini-usb cable; they show up as /dev/ttyACMX.

$ lsusb
Bus 003 Device 002: ID 8087:8001 Intel Corp.
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 005: ID 8087:0a2a Intel Corp.
Bus 001 Device 004: ID 20d2:5740
Bus 001 Device 003: ID 20d2:5740
Bus 001 Device 002: ID 046d:c534 Logitech, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The 20d2:5740 entries are two roboteq controllers. We can check on the serial number for one of them

$ udevadm info -a -n /dev/ttyACM0 | grep '{serial}' | head -n1
    ATTRS{serial}=="SDC2XXX"

Unfortunately, the devices do not seem to have unique serial numbers, so we cannot use that to distinguish between the two roboteq controllers on our robot.

To get around this, we use the set_roboteq_id script to save a unique id in the EEPROM of each controller, and tell udev to use the get_roboteq_id script to include that unique id in a symlink for that device.

$ rosrun roboteq_python set_roboteq_id /dev/ttyACM0 42
Setting idnum for roboteq attached to /dev/ttyACM0 to 42
Saving configuration to EEPROM
ID number set successfully

Now if we read the values back we see the same id numbers.

$ rosrun roboteq_python get_roboteq_id /dev/ttyACM0
42

Next we add a udev script in /etc/udev/rules.d/ telling the kernel to run the get_roboteq_id script and use the ID as part of the device name. See the included file udev/99-roboteq.rules for an example. That file assumes that you have copied the get_roboteq_id to /usr/local/bin/ so that udev knows where to find it.