generated: '2026-08-06'
method: searched
source: https://docs-a1.readthedocs.io/en/latest/communication_messaging.html#error-messages
format: anello-aperr
rfc9457: false
envelope:
  message: '#APERR,<error code>*<CS>'
  emitted_when: an incorrect command is sent to the unit
  transport: configuration port (and data port for RTCM input errors)
  note: >-
    Not RFC 9457 problem+json — this is an embedded ASCII sentence protocol. The
    code is a small integer; there is no type URI, title, detail or instance
    field. Codes are reproduced verbatim from the ANELLO Developer Manual.
error_codes:
- code: 1
  description: No start character (#)
  cause: The sentence did not begin with the '#' lead code identifier.
  remediation: Prefix the sentence with '#'.
- code: 2
  description: Read/Write indicator missing (from #APCFG or #APVEH)
  cause: A configuration sentence omitted the r/w/R/W verb.
  remediation: 'Send #APCFG,<r|w|R|W>,... or #APVEH,<r|w|R|W>,...'
  applies_to: ['#APCFG', '#APVEH']
- code: 3
  description: Incomplete message (checksum missing)
  cause: The sentence ended without the '*' checksum indicator and hex checksum.
  remediation: Append '*' plus the two-digit uppercase XOR checksum, then CRLF.
- code: 4
  description: Incorrect checksum
  cause: The transmitted checksum did not match the XOR of the bytes between '#' and '*'.
  remediation: Recompute the XOR checksum; letters must be uppercase.
- code: 5
  description: Invalid preamble (AP)
  cause: The two characters after '#' were not 'AP'.
  remediation: Use the AP preamble on every ANELLO sentence.
- code: 6
  description: Invalid message type
  cause: The message type following the AP preamble is not one the firmware implements.
  remediation: Use a documented type (CFG, VEH, ODO, PNG, ECH, RST, ...).
- code: 7
  description: Invalid field
  cause: A named configuration field is not recognised for this product/firmware.
  remediation: Check the parameter code against the unit-configuration table for the product.
- code: 8
  description: Invalid value
  cause: The value is outside the allowed set or range for that parameter.
  remediation: Check the allowed values for the parameter.
- code: 9
  description: Flash locked
  cause: A persistent (uppercase W) write was attempted while flash is locked.
  remediation: Unlock flash before writing persistent configuration.
- code: 10
  description: Unexpected character
  cause: Extra characters were sent with an identity/status query that takes no argument.
  applies_to: ['#APPID', '#APSTA', '#APVER', '#APSER', '#APFSN', '#APFHW']
  remediation: Send the query with no additional fields.
- code: 11
  description: Disabled command
  cause: An odometer message was sent while the odometer input is disabled.
  applies_to: ['#APODO']
  remediation: Enable the odometer input before sending #APODO.
positive_responses:
- command: '#APPNG*48'
  response: '#APPNG,0*54'
  meaning: Ping acknowledged; the serial port is correctly configured.
- command: '#APECH,<text>*<CS>'
  response: identical sentence echoed back
  meaning: Port configuration and checksum generator both verified.
- command: '#APRST,0*58'
  response: none
  meaning: The unit resets; output is suspended briefly.
service_level_errors:
  ros:
    source: ros/set_heading_with_unc.srv
    fields:
    - {name: is_success, type: bool}
    - {name: message, type: string}
    note: >-
      The ROS driver's heading-set service returns a boolean plus a free-text
      message rather than an #APERR code.
cross_links:
  conventions: conventions/anello-photonics-conventions.yml
  known_issues: https://docs-a1.readthedocs.io/en/latest/known_limitations.html