Alarm bitmask¶

GET_ALARMS_STATE (ID 20, get) returns a 16-byte (128-bit) bitmask. Each bit is an alarm code from 0x00 to 0x7F. get_alarms decodes the mask into an AlarmSet. The codes are defined in the Dobot Magician ALARM Description V1.0.1.

Bit layout¶

byte_index = code >> 3
bit_index  = code & 0x07

Alarm 0x44 (LIMIT_POS_J3) is raw[8] & 0x10.

Example from the ALARM Description: the mask 01 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00 has bits 0 and 67 set, that is 0x00 (PUBLIC_RESET) and 0x43 (LIMIT_NEG_J2).

Code ranges¶

Range	Group	Description
`0x00` to `0x0F`	System	Reset, unknown command, file system, MCU-FPGA communication, angle sensor.
`0x10` to `0x1F`	Planning	The target of a command cannot be reached.
`0x20` to `0x2F`	Motion	The path of a running move cannot be followed.
`0x30` to `0x3F`	Overspeed	Per-joint overspeed.
`0x40` to `0x4F`	Limit	Per-joint positive and negative limits, and the parallelogram limits.
`0x50` to `0x5F`	Lost step	Per-joint lost step.

The named codes are listed under Alarm.

Exceptions¶

A command that waits for the arm, such as ptp or wait_for, raises a DobotAlarmError subclass chosen by the alarm group, as listed under Alarm groups. A move queued while an alarm is active is dropped. set_home homes also during an alarm.

Formatting¶

AlarmSet.format() returns one line per active alarm. The message of DobotAlarmError uses the same text.

for line in bot.get_alarms().format():
    print(line)

LIMIT_POS_J3: joint 3 (forearm) at its positive limit - jog J3 negative

Encoding¶

pydobotlab.alarms.encode_alarms converts alarm codes back to a mask, for tests:

from pydobotlab.alarms import Alarm, encode_alarms

encode_alarms([Alarm.LIMIT_POS_J3])
# b'\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00'