Protocol Errors

Error messages

When the driver responds with code 1, the message content maps to an exception class on the Python side.

Message	Exception	Meaning
position-is-not-reachable	UnreachableError	out of range or no solution for that pose
R[81]-was-not-set etc.	MotionSetupError	couldn't write a motion parameter register
PR[81]-was-not-set	MotionSetupError	couldn't write the position register
wrong-command	UnsupportedCommandError	driver doesn't recognize it
cannot-convert-joint-vals	CommandError	joint value conversion failed
cannot-get-ins_pwr	CommandError	couldn't read power
cannot-get-reg cannot-set-reg	CommandError	register access failed
cannot-get-preg cannot-set-preg	CommandError	position register access failed
cannot-get-sysvar cannot-set-sysvar	CommandError	variable doesn't exist or type mismatch
cannot-get-sreg cannot-set-sreg	CommandError	string register access failed
cannot-get-jpreg cannot-set-jpreg	CommandError	joint-type position register access failed
everything else	CommandError	catch-all

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Last updated: 2026-08-31