Frame. Msg Not Working with Db_Decode from Cantools
I Want to Use the Can_Msgs/Frame. Msg for Decoding Can Messages Using Db. Decode_Message(Frame. Id, Frame. Data) but It Is Giving Error I Want to Try and Write...
I want to use the can_msgs/Frame.msg for decoding can messages using db.decode_message(Frame.id, Frame.data) but it is giving error
I want to try and write a new Frame.msg format but will it help?
def callback(Frame):
rospy.loginfo(rospy.get_caller_id() + "I heard %s", Frame.data)
Temp = db.decode_message(Frame.id, Frame.data)
temp.data = Temp
pub.publish(temp)
I want to print the message in the dbc format that the cantools package helps decoding.
Error:
File "safa.py", line 42, in callback temp = db.decode_message(Frame.id, Frame.data) File "build/bdist.linux-x86_64/egg/cantools/database/can/database.py", line 379, in decode_message message = self._name_to_message[frame_id_or_name] KeyError: 10
2 Answers
Looking at the cantools documentation for db.decode_message, the KeyError is a bad description/error msg for the following.
db is a database (class cantools.database.can.Database), which stores all the weird encodings we may choose to use with cantools. To decode a message, it must already have an encoding stored within it, using one of the db.add_* methods with the class.
Edit: The definition of the can_msgs/Frame is
std_msgs/Header header
uint32 id
bool is_rtr
bool is_extended
bool is_error
uint8 dlc
uint8[8] data
The data term requires an array/list of 8 uint8 values, not a string. Any CANbus data encoding must finish in this form.
Additionally, ROS provides an interface to the CANbus already: socketcan_bridge can be called in a launch file with your node at the same time.
Before you can decode messages you should setup the database e.g by loading a dbc file:
try:
dbc_file_object = open(dbc_file, 'r')
except IOError as e:
rospy.loginfo('Unable to open file {}'.format(e))
sys.exit(-1)
self.db = cantools.db.load(dbc_file_object)
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