dobot-python

dobot-python copied to clipboard

I added bot.set_end_effector_params (60,0,0) in homing.py. When I ran it, I got the following error:

Traceback (most recent call last): File "examples/homing.py", line 17, in bot.set_end_effector_params(60, 0, 0) File "/home/hoshina/dobot-python/lib/interface.py", line 130, in set_end_effector_params request = Message([0xAA, 0xAA], 2, 60, True, False, [bias_x, bias_y, bias_z], direction='out') File "/home/hoshina/dobot-python/lib/message.py", line 19, in init self.raw_params = self.parse_params('out') File "/home/hoshina/dobot-python/lib/message.py", line 95, in parse_params return parser(self.params) File "/home/hoshina/dobot-python/lib/parsers.py", line 43, in 60: [lambda x: struct.unpack('<' + 'f' * 3, bytearray(x)), None, lambda x: struct.unpack('<Q', bytearray(x))[0], lambda x: list(struct.pack('<' + 'f' * 4, *x))], struct.error: pack expected 4 items for packing (got 3)`

Do you know how to fix the error?

I think this is one of the functions that weren't very well documented in the official documentation for the low-level API.

There might be an error here:

https://github.com/AlexGustafsson/dobot-python/blob/49c36edb4fd9d05bcbfe6ff9d089f8b1edc10ef3/lib/parsers.py#L43.

The set_end_effector_params only seem to be intended to take three parameters, but the parser expects four.

Try to modify lib/parsers.py, line 43 to use 'f' * 3 instead of 'f' * 4:

- 60: [lambda x: struct.unpack('<' + 'f' * 3, bytearray(x)), None, lambda x: struct.unpack('<Q', bytearray(x))[0], lambda x: list(struct.pack('<' + 'f' * 4, *x))],
+ 60: [lambda x: struct.unpack('<' + 'f' * 3, bytearray(x)), None, lambda x: struct.unpack('<Q', bytearray(x))[0], lambda x: list(struct.pack('<' + 'f' * 3, *x))],

Thank you for your reply. When I tried it, But I got the following error:

Traceback (most recent call last): File "examples/homing.py", line 17, in bot.set_end_effector_params(60, 0, 0) File "/home/hoshina/dobot-python/lib/interface.py", line 131, in set_end_effector_params return self.send(request) File "/home/hoshina/dobot-python/lib/interface.py", line 24, in send response = Message.read(self.serial) File "/home/hoshina/dobot-python/lib/message.py", line 63, in read return Message.parse(header + bytes([length]) + payload + checksum) File "/home/hoshina/dobot-python/lib/message.py", line 50, in parse return Message(header, length, id, rw, is_queued, params) File "/home/hoshina/dobot-python/lib/message.py", line 16, in init self.params = self.parse_params('in') File "/home/hoshina/dobot-python/lib/message.py", line 83, in parse_params return parser(self.raw_params) File "/home/hoshina/dobot-python/lib/parsers.py", line 43, in 60: [lambda x: struct.unpack('<' + 'f' * 3, bytearray(x)), None, lambda x: struct.unpack('<Q', bytearray(x))[0], lambda x: list(struct.pack('<' + 'f' * 3, *x))], struct.error: unpack requires a buffer of 12 bytes

After that, Dobot Magician froze and stopped working without restarting the power supply.

Unfortunately this seems to be an instance where the documentation didn't match reality, and I wasn't able to properly test the functionality. I don't have my hands on a robot right now. If you have the time and interest, the documentation I used to implement the functionality is available here: https://download.dobot.cc/product-manual/dobot-magician/pdf/en/Dobot-Communication-Protocol-V1.1.5.pdf.

With some trial and error, you may find how set_end_effector_params should actually be called and fix the mistake in this library.

I'll keep this open, but for now I won't be able to be much of help.