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PUS Command Postprocessor

A postprocessor for handling ECSS PUS commands, according to ECSS-E-ST-70-41C.

This postprocessor will set the length and sequence count in the CCSDS primary header. If configured, it can also calculate a checksum.

Class Name

org.yamcs.pus.PusCommandPostprocessor

Configuration Options

seqCounterName (string)

Name of a shared CCSDS sequence counter. By default each link maintains its own per-APID sequence counter independently of all other links. When two or more links specify the same seqCounterName they share a single per-APID counter, so the target receives a continuous sequence across those links.

If not specified, the counter is local to this link.

errorDetection (map)

If specified, a checksum is appended at the end of each command. Detailed below.

timeEncoding (map)

Configures how the release time is encoded in the generated TC[11,4] command (see the pus11 option below). Sub-keys: implicitPfield (boolean, default true), pfield (integer) and pfieldCont (integer, default -1). If not specified, an implicit CUC P-field of 0x2e is used.

tcoService (string)

Name of a TCO service. When set, the release time written in the TC[11,4] command is the on-board time obtained from that service instead of the raw UTC value.

pus11Crc (boolean)

If true (the default) the generated TC[11,4] command carries a trailing CRC.

pus11Apid (integer)

APID to use for the generated TC[11,4] command. If -1 (the default) the APID of the wrapped command is reused.

pus11 (map)

Enables the PUS 11 time-based scheduling support. Detailed below.

PUS 11 time-based scheduling

A command issued with the pus11ScheduleAt command option (a timestamp) is not sent as-is; instead it is embedded into a TC[11,4] insert activities into the time-based schedule request that releases it on board at the requested time.

The pus11 map configures the optional sub-schedule and scheduling group identifiers that are written into that request. Each sub-section is independent: when it is present the corresponding field is written into the TC[11,4] command and the matching command option is registered so operators can override the value per command; when it is absent neither the field nor the option exist.

subScheduleId (map)

bytes (integer, 1..8, default 1): width of the sub-schedule id field. default (integer, default 0): value used when the pus11SubScheduleId command option is not set.

groupId (map)

bytes (integer, 1..8, default 1): width of the scheduling group id field. default (integer, default 0): value used when the pus11GroupId command option is not set.

sourceId (integer)

Source id written in the secondary header of the generated TC[11,4] command. Default 0.

Example:

commandPostprocessorClassName: org.yamcs.pus.PusCommandPostprocessor
commandPostprocessorArgs:
    errorDetection:
        type: CRC-16-CCIIT
    pus11:
        subScheduleId: { bytes: 1, default: 1 }
        groupId: { bytes: 1, default: 1 }

Error Detection sub-configuration

type (string)

Required. Can take one of the values:

  • 16-SUM: calculates a 16 bits checksum over the entire packet which has to contain an even number of bytes. This checksum is used in Columbus/ISS data.

  • CRC-16-CCIIT: standard CRC algorithm used in PUS and also in CCSDS standards for frame encoding.

  • ISO-16: specified in PUS as alternative to CRC-16-CCIIT.

  • NONE: no error detection will be used, this is the default if the errorDetection map is not present.

initialValue (integer)

Used when the type is CRC-16-CCIIT to specify the initial value used for the algorithm. Default: 0xFFFF.

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