ECSS Package

The following classes can be used to create and read ECSS PUS-C packets:

spacepackets.ecss.PusTc
spacepackets.ecss.PusTm

ECSS Fields

class spacepackets.ecss.fields.PacketFieldBase(ptc: 'int', pfc: 'int')

Bases: object

pfc: int

ptc: int

class spacepackets.ecss.fields.PacketFieldEnum(pfc: int, val: int)

Bases: PacketFieldBase

static check_pfc(pfc: int) → int: Check for byte alignment of the PFC. Do not use this if to plan to pack multiple enumerations into one byte

len() → int: Return the length in bytes. This will raise a ValueError for non-byte-aligned PFC values.

pack() → bytearray

classmethod unpack(data: bytes | bytearray, pfc: int) → PacketFieldEnum

Construct from a raw bytestream.

Raises:: BytesTooShortError – Raw bytestream too short.

classmethod with_byte_size(num_bytes: int, val: int) → PacketFieldEnum

class spacepackets.ecss.fields.PacketFieldU16(val: int): Bases: PacketFieldEnum

class spacepackets.ecss.fields.PacketFieldU32(val: int): Bases: PacketFieldEnum

class spacepackets.ecss.fields.PacketFieldU8(val: int): Bases: PacketFieldEnum

class spacepackets.ecss.fields.PfcReal(value)

Bases: IntEnum

An enumeration.

DOUBLE_PRECISION_IEEE = 2

DOUBLE_PRECISION_MIL_STD_6_OCTETS = 4

FLOAT_PRECISION_MIL_STD_4_OCTETS = 3

FLOAT_SIMPLE_PRECISION_IEEE = 1

class spacepackets.ecss.fields.PfcSigned(value)

Bases: IntEnum

An enumeration.

EIGHT_BYTES = 16

ELEVEN_BIT = 7

FIFTEEN_BIT = 11

FIVE_BIT = 1

FOURTEEN_BIT = 10

FOUR_BIT = 0

FOUR_BYTES = 14

NINE_BIT = 5

ONE_BYTE = 4

SEVEN_BIT = 3

SIX_BIT = 2

SIX_BYTES = 15

TEN_BIT = 6

THIRTEEN_BIT = 9

THREE_BYTES = 13

TWELVE_BIT = 8

TWO_BYTES = 12

class spacepackets.ecss.fields.PfcUnsigned(value)

Bases: IntEnum

An enumeration.

EIGHT_BYTES = 16

ELEVEN_BIT = 7

FIFTEEN_BIT = 11

FIVE_BIT = 1

FOURTEEN_BIT = 10

FOUR_BIT = 0

FOUR_BYTES = 14

NINE_BIT = 5

ONE_BIT = 17

ONE_BYTE = 4

SEVEN_BIT = 3

SIX_BIT = 2

SIX_BYTES = 15

TEN_BIT = 6

THIRTEEN_BIT = 9

THREE_BIT = 19

THREE_BYTES = 13

TWELVE_BIT = 8

TWO_BIT = 18

TWO_BYTES = 12

class spacepackets.ecss.fields.Ptc(value)

Bases: IntEnum

An enumeration.

ABSOLUTE_TIME = 9

BIT_STRING = 6

BOOLEAN = 1

CHARACTER_STRING = 8

DEDUCED = 11

ENUMERATED = 2

OCTET_STRING = 7

PACKET = 12

REAL = 5

RELATIVE_TIME = 10

SIGNED = 4

UNSIGNED = 3

ECSS TC Submodule

This module contains the PUS telecommand class representation to pack telecommands, most notably the PusTelecommand class.

exception spacepackets.ecss.tc.InvalidTcCrc16Error(tc: PusTc | None): Bases: Exception

class spacepackets.ecss.tc.PusTc(service: int, message_subtype: int | None = None, has_checksum: bool = True, apid: int = 0, app_data: bytes | bytearray = b'', seq_count: int = 0, source_id: int = 0, ack_flags: int = 15, subservice: int | None = None)

Bases: AbstractSpacePacket

Class representation of a PUS telecommand. Can be converted to the raw byte representation but also unpacked from a raw byte stream. Only PUS C telecommands are supported.

>>> ping_tc = PusTc(service=17, message_subtype=1, seq_count=22, apid=0x01)
>>> ping_tc.service
17
>>> ping_tc.message_subtype
1
>>> ping_tc.pack().hex(sep=',')
'18,01,c0,16,00,06,2f,11,01,00,00,ab,62'

Initiate a PUS telecommand from the given parameters. The raw byte representation can then be retrieved with the pack() function.

Parameters:

service – PUS service number
message_subtype – PUS message subtype number
apid – Application Process ID as specified by CCSDS
seq_count – Source Sequence Count. Application should take care of incrementing this. Limited to 2 to the power of 14 by the number of bits in the header
app_data – Application data in the Packet Data Field
source_id – Source ID will be supplied as well. Can be used to distinguish different packet sources (e.g. different ground stations)

Raises:

ValueError – Invalid input parameters

property apid: int

property app_data: bytes

calc_crc() → None: Can be called to calculate the CRC16. Also sets the internal CRC16 field.

property ccsds_version: int

property crc16: bytes | None: Will be the raw CRC16 if the telecommand was created using unpack(), pack() was called at least once or calc_crc() was called at least once.

classmethod empty() → PusTc

classmethod from_composite_fields(sp_header: SpacePacketHeader, sec_header: PusTcDataFieldHeader, app_data: bytes = b'', has_checksum: bool = True) → PusTc

classmethod from_sp_header(sp_header: SpacePacketHeader, service: int, message_subtype: int | None = None, app_data: bytes = b'', source_id: int = 0, ack_flags: int = 15, has_checksum: bool = True, subservice: int | None = None) → PusTc

static get_data_length(app_data_len: int, secondary_header_len: int, has_checksum: bool) → int: Retrieve size of TC packet in bytes. Formula according to PUS Standard: C = (Number of octets in packet data field) - 1. The size of the TC packet is the size of the packet secondary header with source ID + the length of the application data + length of the CRC16 checksum - 1

property has_checksum: bool

property message_subtype: int

pack(recalc_crc: bool = True) → bytearray

Serializes the TC data fields into a bytearray.

Parameters:: recalc_crc – Can be set to False if the CRC was previous calculated and no fields were changed. This is set to True by default to ensure the CRC is always valid by default, even if the user changes arbitrary fields after TC creation.

pack_command_tuple() → tuple[bytearray, PusTc]: Pack a tuple consisting of the raw packet as the first entry and the class representation as the second entry

Deprecated since version v0.14.0rc3: use pack and the class itself to build this instead

property packet_id: PacketId

property packet_len: int: Retrieve the full packet size when packed :return: Size of the TM packet based on the space packet header data length field. The space packet data field is the full length of data field minus one without the space packet header.

property packet_seq_control: PacketSeqCtrl

property seq_count: int

property service: int

property source_id: int

property subservice: int: Deprecated since version v0.32.0: use message_subtype property instead

to_space_packet() → SpacePacket: Retrieve the generic CCSDS space packet representation. This also calculates the CRC16 before converting the PUS TC to a generic Space Packet

classmethod unpack(data: bytes | bytearray) → PusTc

Create an instance from a raw bytestream, expecting a checksum and verifying it as well.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTcCrc16Error – Invalid CRC16 checksum.

classmethod unpack_generic(data: bytes | bytearray, has_checksum: bool, verify_checksum: bool) → PusTc

Create an instance from a raw bytestream.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTcCrc16Error – Invalid CRC16.

classmethod unpack_no_checksum(data: bytes | bytearray) → PusTc

Create an instance from a raw bytestream with no checksum.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTcCrc16Error – Invalid CRC16.

class spacepackets.ecss.tc.PusTcDataFieldHeader(service: int, message_subtype: int | None = None, source_id: int = 0, ack_flags: int = 15, subservice: int | None = None)

Bases: object

Create a PUS TC data field header instance

Parameters:

service
message_subtype
source_id
ack_flags

PUS_C_SEC_HEADER_LEN = 5

classmethod get_header_size() → int

pack() → bytearray

property subservice: int: Deprecated since version v0.32.0: use message_subtype property instead

classmethod unpack(data: bytes | bytearray) → PusTcDataFieldHeader

Unpack a TC data field header.

Parameters:: data – Start of raw data belonging to the TC data field header
Raises:: BytesTooShortError – Passed data too short.
Returns:

spacepackets.ecss.tc.PusTelecommand: alias of PusTc

spacepackets.ecss.tc.generate_crc(data: bytearray) → bytes: Takes the application data, appends the CRC16 checksum and returns resulting bytearray

spacepackets.ecss.tc.generate_packet_crc(tc_packet: bytearray) → bytes: Removes current Packet Error Control, calculates new CRC16 checksum and adds it as correct Packet Error Control Code. Reference: ECSS-E70-41A p. 207-212

ECSS TM Submodule

This module contains import PUS TM packet classes, most notably the spacepackets.ecss.tm.PusTelemetry class.

class spacepackets.ecss.tm.AbstractPusTm

Bases: AbstractSpacePacket

Generic abstraction for PUS TM packets

get_sp_header() → SpacePacketHeader: Deprecated since version v0.14.0rc2: use sp_header property instead

property message_subtype: int

abstract property service: int

abstract property source_data: bytes

abstract property sp_header: SpacePacketHeader

property subservice: int

abstract property timestamp: bytes

exception spacepackets.ecss.tm.InvalidTmCrc16Error(tm: PusTm): Bases: Exception

class spacepackets.ecss.tm.ManagedParams(timestamp_len: int, has_checksum: bool = True, verify_checksum: bool = True)

Bases: object

Managed parameters are used defined and are usually fixed for a given mission.

has_checksum: bool = True

timestamp_len: int

verify_checksum: bool = True

class spacepackets.ecss.tm.MiscParams(spacecraft_time_ref: 'int' = 0, packet_version: 'int' = 0)

Bases: object

packet_version: int = 0

spacecraft_time_ref: int = 0

spacepackets.ecss.tm.PusTelemetry: alias of PusTm

class spacepackets.ecss.tm.PusTm(service: int, message_subtype: int | None = None, timestamp: bytes | bytearray = b'', has_checksum: bool = True, source_data: bytes | bytearray = b'', apid: int = 0, seq_count: int = 0, message_counter: int = 0, destination_id: int = 0, misc_params: MiscParams | None = None, subservice: int | None = None)

Bases: AbstractPusTm

Generic PUS telemetry class representation.

Can be used to generate TM packets using a high level interface with the default constructor, or to deserialize TM packets from a raw byte stream using the unpack() method. This implementation only supports PUS C.

Deserialization of PUS telemetry requires the timestamp length to be known. If the size of the timestamp is variable but can be determined from the data, a look-ahead should be performed on the raw data. The PUS_TM_TIMESTAMP_OFFSET (13) can be used to do this, assuming that the timestamp length can be extracted from the timestamp itself.

The following doc example cuts off the timestamp (7 byte CDS Short) and the CRC16 from the ping packet because those change regularly.

>>> ping_tm = PusTm(service=17, message_subtype=2, seq_count=5, apid=0x01, timestamp=CdsShortTimestamp.now().pack())
>>> ping_tm.service
17
>>> ping_tm.message_subtype
2
>>> ping_tm.pack()[:-9].hex(sep=',')
'08,01,c0,05,00,0f,20,11,02,00,00,00,00'

CDS_SHORT_SIZE = 7

PUS_TIMESTAMP_SIZE = 7

property apid: int

calc_crc() → None: Can be called to calculate the CRC16

property ccsds_version: int

property crc16: bytes | None: Will be the raw CRC16 if the telecommand was created using unpack() or pack() was called at least once.

static data_len_from_src_len_timestamp_len(timestamp_len: int, source_data_len: int, has_checksum: bool) → int

Retrieve size of TM packet data header in bytes. Only support PUS C Formula according to PUS Standard: C = (Number of octets in packet source data field) - 1. The size of the TM packet is the size of the packet secondary header with the timestamp + the length of the application data + PUS timestamp size + length of the CRC16 checksum - 1

Parameters:

source_data_len – Length of the source (user) data
timestamp_len – Length of the used timestamp

classmethod empty() → PusTm

classmethod from_composite_fields(sp_header: SpacePacketHeader, sec_header: PusTmSecondaryHeader, tm_data: bytes, has_checksum: bool = True) → PusTm

get_full_packet_string(print_format: PrintFormats = PrintFormats.HEX) → str: Deprecated since version 0.14.0rc3: use pack and get_printable_data_string or the hex method on bytearray instead

get_source_data_string(print_format: PrintFormats = PrintFormats.HEX) → str: Returns the source data string

Deprecated since version 0.14.0rc3: use the source_data property and the hex method on bytearray instead

property has_checksum: bool

property message_subtype: int: Get the message subtype ID :return: Message subtype ID

pack(recalc_crc: bool = True) → bytearray

Serializes the packet into a raw bytearray.

Parameters:: recalc_crc – Can be set to False if the CRC was previous calculated and no fields were changed. This is set to True by default to ensure the CRC is always valid by default, even if the user changes arbitrary fields after TM creation.

property packet_id: PacketId

property packet_len: int: Retrieve the full packet size when packed :return: Size of the TM packet based on the space packet header data length field. The space packet data field is the full length of data field minus one without the space packet header.

property packet_seq_control: PacketSeqCtrl

print_full_packet_string(print_format: PrintFormats = PrintFormats.HEX) → None: Print the full TM packet in a clean format.

Deprecated since version 0.14.0rc3: use pack and get_printable_data_string or the hex method on bytearray instead

print_source_data(print_format: PrintFormats = PrintFormats.HEX) → None: Prints the TM source data in a clean format

Deprecated since version 0.14.0rc3: use print, the source_data property and the hex method on bytearray instead

property seq_count: int: Get the source sequence count :return: Source Sequence Count (see below, or PUS documentation)

property seq_flags: SequenceFlags

property service: int: Get the service type ID :return: Service ID

static service_from_bytes(raw_bytearray: bytearray) → int

Determine the service ID from a raw packet, which can be used for packet deserialization.

It is assumed that the user already checked that the raw bytearray contains a PUS packet and only basic sanity checks will be performed. :raise ValueError: If raw bytearray is too short

property source_data: bytes

property sp_header: SpacePacketHeader

property subservice: int: Get the subservice ID :return: Subservice ID

Deprecated since version v0.32.0: use message_subtype property instead

property timestamp: bytes

property tm_data: bytes

TM source data (raw)

Type:: return

to_space_packet() → SpacePacket: Retrieve the generic CCSDS space packet representation. This also calculates the CRC16 before converting the PUS TC to a generic Space Packet

classmethod unpack(data: bytes | bytearray, timestamp_len: int) → PusTm

Attempts to construct a generic PusTelemetry class given a raw bytearray. This unpacker method expects a checksum and also verifies it.

Parameters:

data – Raw bytes containing the PUS telemetry packet.
time_reader – Time provider to read the timestamp. If the timestamp field is empty, you can supply None here.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTmCrc16Error – Invalid CRC16.

classmethod unpack_generic(data: bytes | bytearray, managed_params: ManagedParams) → PusTm

Attempts to construct a generic PusTelemetry class given a raw bytearray.

Parameters:

data – Raw bytes containing the PUS telemetry packet.
time_reader – Time provider to read the timestamp. If the timestamp field is empty, you can supply None here.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTmCrc16Error – Invalid CRC16.

classmethod unpack_no_checksum(data: bytes | bytearray, timestamp_len: int) → PusTm

Attempts to construct a generic PusTelemetry class given a raw bytearray without a checksum.

Parameters:

data – Raw bytes containing the PUS telemetry packet.
time_reader – Time provider to read the timestamp. If the timestamp field is empty, you can supply None here.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTmCrc16Error – Invalid CRC16.

class spacepackets.ecss.tm.PusTmSecondaryHeader(service: int, message_subtype: int | None = None, timestamp: bytes | bytearray = b'', message_counter: int = 0, dest_id: int = 0, spacecraft_time_ref: int = 0, subservice: int | None = None)

Bases: object

Unpacks the PUS telemetry packet secondary header. Currently only supports CDS short timestamps and PUS C

Create a PUS telemetry secondary header object.

Parameters:

service
message_subtype
time_provider – Time field provider which can provide or read a time field
message_counter – 8 bit counter for PUS A, 16 bit counter for PUS C
dest_id – Destination ID if PUS C is used
spacecraft_time_ref – Space time reference if PUS C is used

MIN_LEN = 7

property header_size: int

pack() → bytearray

property subservice: int: Deprecated since version v0.32.0: use message_subtype property instead

classmethod unpack(data: bytes | bytearray, timestamp_len: int) → PusTmSecondaryHeader

Unpack the PUS TM secondary header from the raw packet starting at the header index.

Parameters:

data – Raw data. Please note that the passed buffer should start where the actual header start is.
timestamp_len – Expected timestamp length.

Raises:

ValueError – bytearray too short or PUS version missmatch.

Returns:

ECSS Request ID Submodule

class spacepackets.ecss.req_id.RequestId(tc_packet_id: PacketId, tc_psc: PacketSeqCtrl, ccsds_version: int = 0)

Bases: object

The request ID which is used to identify PUS telecommands. The request ID consists of the first two bytes of the CCSDS primary header. It is primarily used to verify the execution of sent telecommands.

>>> from spacepackets.ccsds import PacketType, SequenceFlags
>>> packet_id = PacketId(ptype=PacketType.TC, sec_header_flag=False, apid=0x22)
>>> psc = PacketSeqCtrl(seq_flags=SequenceFlags.UNSEGMENTED, seq_count=17)
>>> req_id = RequestId(packet_id, psc)
>>> req_id
RequestId(tc_packet_id=PacketId(ptype=<PacketType.TC: 1>, sec_header_flag=False, apid=34), tc_psc=PacketSeqCtrl(seq_flags=<SequenceFlags.UNSEGMENTED: 3>, seq_count=17), ccsds_version=0)
>>> struct.pack("!I", req_id.as_u32()).hex(sep=",")
'10,22,c0,11'

as_u32() → int

classmethod empty() → RequestId

classmethod from_pus_tc(pus_tc: PusTc) → RequestId

classmethod from_sp_header(header: SpacePacketHeader) → RequestId

pack() → bytes

classmethod unpack(tm_data: bytes | bytearray) → RequestId

ECSS PUS 1 Verification Service Submodule

ECSS PUS Service 1 Verification

class spacepackets.ecss.pus_1_verification.FailureNotice(code: PacketFieldEnum, data: bytes)

Bases: object

len() → int

pack() → bytes

classmethod unpack(data: bytes | bytearray, num_bytes_err_code: int, num_bytes_data: int | None = None) → FailureNotice

exception spacepackets.ecss.pus_1_verification.InvalidVerifParamsError: Bases: Exception

class spacepackets.ecss.pus_1_verification.ManagedParamsVerification(bytes_step_id: 'int' = 1, bytes_err_code: 'int' = 1)

Bases: object

bytes_err_code: int = 1

bytes_step_id: int = 1

class spacepackets.ecss.pus_1_verification.MessageSubtype(value)

Bases: IntEnum

An enumeration.

INVALID = 0

TM_ACCEPTANCE_FAILURE = 2

TM_ACCEPTANCE_SUCCESS = 1

TM_COMPLETION_FAILURE = 8

TM_COMPLETION_SUCCESS = 7

TM_START_FAILURE = 4

TM_START_SUCCESS = 3

TM_STEP_FAILURE = 6

TM_STEP_SUCCESS = 5

class spacepackets.ecss.pus_1_verification.Service1Tm(apid: int, message_subtype: MessageSubtype | int | None = None, timestamp: bytes | bytearray = b'', verif_params: VerificationParams | None = None, seq_count: int = 0, destination_id: int = 0, misc_params: MiscParams | None = None, subservice: MessageSubtype | int | None = None)

Bases: AbstractPusTm

Service 1 TM class representation.

property ccsds_version: int

property error_code: PacketFieldEnum | None

property failure_notice: FailureNotice | None

classmethod from_tm(tm: PusTm, verif_params: ManagedParamsVerification) → Service1Tm

property has_failure_notice: bool

property is_step_reply: bool

property message_subtype: int

pack() → bytearray

property packet_id: PacketId

property packet_seq_control: PacketSeqCtrl

property service: int

property source_data: bytes

property sp_header: SpacePacketHeader

property step_id: PacketFieldEnum | None: Retrieve the step number. Returns NONE if this packet does not have a step ID

property subservice: int: Deprecated since version v0.32.0: use message_subtype property instead

property tc_req_id: RequestId

property timestamp: bytes

classmethod unpack(data: bytes, managed_params: ManagedParams, verif_params: ManagedParamsVerification) → Service1Tm

Parse a service 1 telemetry packet.

Parameters:

params
data

Raises:

ValueError – MessageSubtype invalid.
BytesTooShortError – passed data too short
TmSourceDataTooShortError – TM source data too short.

Returns:

spacepackets.ecss.pus_1_verification.Subservice: alias of MessageSubtype

class spacepackets.ecss.pus_1_verification.VerificationParams(req_id: 'RequestId', step_id: 'StepId | None' = None, failure_notice: 'FailureNotice | None' = None)

Bases: object

failure_notice: FailureNotice | None = None

len() → int

pack() → bytearray

req_id: RequestId

step_id: PacketFieldEnum | None = None

verify_against_message_subtype(message_subtype: MessageSubtype) → None

verify_against_subservice(subservice: MessageSubtype) → None: Deprecated since version v0.32.0: use verify_against_message_subtype instead

spacepackets.ecss.pus_1_verification.create_acceptance_failure_tm(apid: int, pus_tc: PusTc, failure_notice: FailureNotice, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_acceptance_success_tm(apid: int, pus_tc: PusTc, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_completion_failure_tm(apid: int, pus_tc: PusTc, failure_notice: FailureNotice, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_completion_success_tm(apid: int, pus_tc: PusTc, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_start_failure_tm(apid: int, pus_tc: PusTc, failure_notice: FailureNotice, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_start_success_tm(apid: int, pus_tc: PusTc, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_step_failure_tm(apid: int, pus_tc: PusTc, step_id: PacketFieldEnum, failure_notice: FailureNotice, timestamp: bytes) → Service1Tm

spacepackets.ecss.pus_1_verification.create_step_success_tm(apid: int, pus_tc: PusTc, step_id: PacketFieldEnum, timestamp: bytes) → Service1Tm

ECSS PUS 3 Housekeeping Service Submodule

class spacepackets.ecss.pus_3_hk.MessageSubtype(value)

Bases: IntEnum

An enumeration.

TC_DISABLE_PERIODIC_DIAGNOSTICS_GEN = 8

TC_DISABLE_PERIODIC_HK_GEN = 6

TC_ENABLE_PERIODIC_DIAGNOSTICS_GEN = 7

TC_ENABLE_PERIODIC_HK_GEN = 5

TC_GENERATE_ONE_DIAGNOSTICS_REPORT = 28

TC_GENERATE_ONE_PARAMETER_REPORT = 27

TC_MODIFY_DIAGNOSTICS_REPORT_COLLECTION_INTERVAL = 32

TC_MODIFY_PARAMETER_REPORT_COLLECTION_INTERVAL = 31

TM_DIAGNOSTICS_REPORT = 26

TM_DIAG_DEFINITION_REPORT = 12

TM_HK_DEFINITIONS_REPORT = 10

TM_HK_REPORT = 25

TM_REPORT_DIAG_REPORT_STRUCTURES = 11

TM_REPORT_HK_REPORT_STRUCTURES = 9

ECSS TC PUS A Submodule

This module contains the PUS telecommand class representation to pack telecommands, most notably the PusTelecommand class for the PUS A standard (version number 0b001).

exception spacepackets.ecss.tc_pus_a.InvalidTcCrc16Error(tc: PusTc): Bases: Exception

class spacepackets.ecss.tc_pus_a.PusTc(service: int, subservice: int, apid: int = 0, app_data: bytes | bytearray = b'', source_id: UnsignedByteField | None = None, seq_count: int = 0, ack_flags: int = 15)

Bases: AbstractSpacePacket

Class representation of a PUS telecommand. Can be converted to the raw byte representation but also unpacked from a raw byte stream.

>>> ping_tc = PusTc(service=17, subservice=1, seq_count=22, apid=0x01)
>>> ping_tc.service
17
>>> ping_tc.subservice
1
>>> ping_tc.pack().hex(sep=',')
'18,01,c0,16,00,04,1f,11,01,41,10'

Initiate a PUS telecommand from the given parameters. The raw byte representation can then be retrieved with the pack() function.

Parameters:

service – PUS service number
subservice – PUS subservice number
apid – Application Process ID as specified by CCSDS
seq_count – Source Sequence Count. Application should take care of incrementing this. Limited to 2 to the power of 14 by the number of bits in the header
app_data – Application data in the Packet Data Field
source_id – Source ID can be supplied as well. Can be used to distinguish different packet sources (e.g. different ground stations)

Raises:

ValueError – Invalid input parameters

property apid: int

property app_data: bytes

calc_crc() → None: Can be called to calculate the CRC16. Also sets the internal CRC16 field.

property ccsds_version: int

property crc16: bytes | None: Will be the raw CRC16 if the telecommand was created using unpack(), pack() was called at least once or calc_crc() was called at least once.

classmethod empty() → PusTc

classmethod from_composite_fields(sp_header: SpacePacketHeader, sec_header: PusTcDataFieldHeader, app_data: bytes = b'') → PusTc

classmethod from_sp_header(sp_header: SpacePacketHeader, service: int, subservice: int, app_data: bytes = b'', source_id: UnsignedByteField | None = None, spare_bytes: int = 0, ack_flags: int = 15) → PusTc

static get_data_length(app_data_len: int, secondary_header_len: int) → int: Retrieve size of TC packet in bytes. Formula according to PUS Standard: C = (Number of octets in packet data field) - 1. The size of the TC packet is the size of the packet secondary header with source ID + the length of the application data + length of the CRC16 checksum - 1

pack(recalc_crc: bool = True) → bytearray

Serializes the TC data fields into a bytearray.

Parameters:: recalc_crc – Can be set to False if the CRC was previous calculated and no fields were changed. This is set to True by default to ensure the CRC is always valid by default, even if the user changes arbitrary fields after TC creation.

pack_command_tuple() → tuple[bytearray, PusTc]: Pack a tuple consisting of the raw packet as the first entry and the class representation as the second entry

Deprecated since version v0.14.0rc3: use pack and the class itself to build this instead

property packet_id: PacketId

property packet_len: int: Retrieve the full packet size when packed :return: Size of the TM packet based on the space packet header data length field. The space packet data field is the full length of data field minus one without the space packet header.

property packet_seq_control: PacketSeqCtrl

property seq_count: int

property service: int

property source_id: UnsignedByteField | None

property subservice: int

to_space_packet() → SpacePacket: Retrieve the generic CCSDS space packet representation. This also calculates the CRC16 before converting the PUS TC to a generic Space Packet

classmethod unpack(data: bytes | bytearray, source_id_len: int | None = None, spare_bytes: int = 0) → PusTc

Create an instance from a raw bytestream.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTcCrc16Error – Invalid CRC16.

class spacepackets.ecss.tc_pus_a.PusTcDataFieldHeader(service: int, subservice: int, source_id: UnsignedByteField | None, ack_flags: int = 15, spare_bytes: int = 0)

Bases: object

Create a PUS A TC data field header instance

header_size() → int

classmethod header_size_for_config(source_id_len: int | None, spare_bytes: int = 0) → int

pack() → bytearray

classmethod unpack(data: bytes | bytearray, source_id_len: int | None = None, spare_bytes: int = 0) → PusTcDataFieldHeader

Unpack a PUS A TC data field header.

Parameters:

data – Start of raw data belonging to the TC data field header

Raises:

ValueError – Invalid PUS standard field which is not PUS A.
BytesTooShortError – Passed data too short.

Returns:

spacepackets.ecss.tc_pus_a.PusTelecommand: alias of PusTc

ECSS TM PUS A Submodule

This module contains import PUS TM packet classes, most notably the spacepackets.ecss.tm.PusTelemetry class.

exception spacepackets.ecss.tm_pus_a.InvalidTmCrc16Error(tm: PusTm): Bases: Exception

spacepackets.ecss.tm_pus_a.PusTelemetry: alias of PusTm

class spacepackets.ecss.tm_pus_a.PusTm(service: int, subservice: int, timestamp: bytes | bytearray, source_data: bytes | bytearray = b'', apid: int = 0, seq_count: int = 0, message_counter: int | None = None, destination_id: UnsignedByteField | None = None, packet_version: int = 0, sec_header_spare_bytes: int = 0)

Bases: AbstractPusTm

Generic PUS telemetry class representation.

Can be used to generate TM packets using a high level interface with the default constructor, or to deserialize TM packets from a raw byte stream using the unpack() method. This implementation only supports PUS C.

Deserialization of PUS telemetry requires the timestamp length to be known. If the size of the timestamp is variable but can be determined from the data, a look-ahead should be performed on the raw data. The PUS_TM_TIMESTAMP_OFFSET (13) can be used to do this, assuming that the timestamp length can be extracted from the timestamp itself.

The following doc example cuts off the timestamp (7 byte CDS Short) and the CRC16 from the ping packet because those change regularly.

>>> ping_tm = PusTm(service=17, subservice=2, seq_count=5, apid=0x01, timestamp=CdsShortTimestamp.now().pack())
>>> ping_tm.service
17
>>> ping_tm.subservice
2
>>> ping_tm.pack()[:-9].hex(sep=',')
'08,01,c0,05,00,0b,10,11,02'

CDS_SHORT_SIZE = 7

PUS_TIMESTAMP_SIZE = 7

property apid: int

calc_crc() → None: Can be called to calculate the CRC16

property ccsds_version: int

property crc16: bytes | None: Will be the raw CRC16 if the telecommand was created using unpack() or pack() was called at least once.

static data_len_from_src_len_timestamp_len(timestamp_len: int, source_data_len: int, has_message_counter: bool, dest_id_len: None | int) → int

Retrieve size of TM packet data header in bytes. Only support PUS C Formula according to PUS Standard: C = (Number of octets in packet source data field) - 1. The size of the TM packet is the size of the packet secondary header with the timestamp + the length of the application data + PUS timestamp size + length of the CRC16 checksum - 1

Parameters:

source_data_len – Length of the source (user) data
timestamp_len – Length of the used timestamp

classmethod empty() → PusTm

classmethod from_composite_fields(sp_header: SpacePacketHeader, sec_header: PusTmSecondaryHeader, tm_data: bytes) → PusTm

get_full_packet_string(print_format: PrintFormats = PrintFormats.HEX) → str: Deprecated since version 0.14.0rc3: use pack and get_printable_data_string or the hex method on bytearray instead

get_source_data_string(print_format: PrintFormats = PrintFormats.HEX) → str: Returns the source data string

Deprecated since version 0.14.0rc3: use the source_data property and the hex method on bytearray instead

pack(recalc_crc: bool = True) → bytearray

Serializes the packet into a raw bytearray.

Parameters:: recalc_crc – Can be set to False if the CRC was previous calculated and no fields were changed. This is set to True by default to ensure the CRC is always valid by default, even if the user changes arbitrary fields after TM creation.

property packet_id: PacketId

property packet_len: int: Retrieve the full packet size when packed :return: Size of the TM packet based on the space packet header data length field. The space packet data field is the full length of data field minus one without the space packet header.

property packet_seq_control: PacketSeqCtrl

print_full_packet_string(print_format: PrintFormats = PrintFormats.HEX) → None: Print the full TM packet in a clean format.

Deprecated since version 0.14.0rc3: use pack and get_printable_data_string or the hex method on bytearray instead

print_source_data(print_format: PrintFormats = PrintFormats.HEX) → None: Prints the TM source data in a clean format

Deprecated since version 0.14.0rc3: use print, the source_data property and the hex method on bytearray instead

property seq_count: int: Get the source sequence count :return: Source Sequence Count (see below, or PUS documentation)

property seq_flags: SequenceFlags

property service: int: Get the service type ID :return: Service ID

static service_from_bytes(raw_bytearray: bytearray) → int

Determine the service ID from a raw packet, which can be used for packet deserialization.

It is assumed that the user already checked that the raw bytearray contains a PUS packet and only basic sanity checks will be performed. :raise ValueError: If raw bytearray is too short

property source_data: bytes

property sp_header: SpacePacketHeader

property subservice: int: Get the subservice type ID :return: Subservice ID

property timestamp: bytes

property tm_data: bytes

TM source data (raw)

Type:: return

to_space_packet() → SpacePacket: Retrieve the generic CCSDS space packet representation. This also calculates the CRC16 before converting the PUS TC to a generic Space Packet

classmethod unpack(data: bytes | bytearray, timestamp_len: int, has_message_counter: bool, dest_id_len: int | None) → PusTm

Attempts to construct a generic PusTelemetry class given a raw bytearray.

Parameters:

data – Raw bytes containing the PUS telemetry packet.
time_reader – Time provider to read the timestamp. If the timestamp field is empty, you can supply None here.

Raises:

BytesTooShortError – Passed bytestream too short.
ValueError – Unsupported PUS version.
InvalidTmCrc16Error – Invalid CRC16.

class spacepackets.ecss.tm_pus_a.PusTmSecondaryHeader(service: int, subservice: int, timestamp: bytes | bytearray, message_counter: int | None, dest_id: UnsignedByteField | None = None, spare_bytes: int = 0)

Bases: object

Unpacks the PUS telemetry packet secondary header. Currently only supports CDS short timestamps and PUS C

Create a PUS telemetry secondary header object.

Parameters:

service
subservice
time_provider – Time field provider which can provide or read a time field
message_counter – 8 bit counter for PUS A, 16 bit counter for PUS C
dest_id – Destination ID if PUS C is used
spacecraft_time_ref – Space time reference if PUS C is used

MIN_LEN = 3

property header_size: int

pack() → bytearray

classmethod unpack(data: bytes | bytearray, timestamp_len: int, has_message_counter: bool = False, dest_id_len: int | None = None, spare_bytes: int = 0) → PusTmSecondaryHeader

Unpack the PUS TM secondary header from the raw packet starting at the header index.

Parameters:

data – Raw data. Please note that the passed buffer should start where the actual header start is.
timestamp_len – Expected timestamp length.

Raises:

ValueError – bytearray too short or PUS version missmatch.

Returns: