Telemetry Configuration

Telemetry Definition Files

Telemetry definition files define the telemetry packets that can be received and processed from COSMOS targets. One large file can be used to define the telemetry packets, or multiple files can be used at the user’s discretion. Telemetry definition files are placed in the config/TARGET/cmd_tlm directory and are processed alphabetically. Therefore if you have some telemetry files that depend on others, e.g. they override or extend existing telemetry, they must be named last. The easist way to do this is to add an extension to an existing file name. For example, if you already have tlm.txt you can create tlm_override.txt for telemetry that depends on the definitions in tlm.txt. Note that due to the way the ASCII Table is structured, files beginning with capital letters are processed before lower case letters.

When defining telemetry items you can choose from the following data types: INT, UINT, FLOAT, DERIVED, STRING, BLOCK. These correspond to integers, unsigned integers, floating point numbers, derived values of 0 size which aren’t actually physically defined in the packet, strings and binary blocks of data. The only difference between a STRING and BLOCK is when COSMOS reads a STRING type it stops reading when it encounters a null byte (0). This shows up when displaying the value in Packet Viewer or Tlm Viewer and in the output of Telemetry Extractor.

TELEMETRY

Defines a new telemetry packet

Parameter	Description	Required
Target	Name of the target this telemetry packet is associated with Valid Values: Any Target Name	True
Command	Name of this telemetry packet. Also referred to as its mnemonic. Must be unique to telemetry packets in this target. Ideally will be as short and clear as possible.	True
Endianness	Indicates if the data in this packet is in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	True
Description	Description of this telemetry packet which must be enclosed with quotes	False

Example Usage:

TELEMETRY SYSTEM LIMITS_CHANGE BIG_ENDIAN "COSMOS limits change"

SELECT_TELEMETRY

Selects an existing telemetry packet for editing

Typically used in a separate configuration file from where the original telemetry is defined to override or add to the existing telemetry definition

Parameter	Description	Required
Target Name	Name of the target this telemetry packet is associated with Valid Values: Any Target Name	True
Command Name	Name of the telemetry packet to select	True

Example Usage:

SELECT_TELEMETRY SYSTEM LIMITS_CHANGE

LIMITS_GROUP

Defines a group of related limits Items

Limits groups contain telemetry items that can be enabled and disabled together. It can be used to group related limits as a subsystem that can be enabled or disabled as that particular subsystem is powered (for example). To enable a group call the enable_limits_group(“NAME”) method in Script Runner. To disable a group call the disable_limits_group(“NAME”) in Script Runner. Items can belong to multiple groups but the last enabled or disabled group “wins”. For example, if an item belongs to GROUP1 and GROUP2 and you first enable GROUP1 and then disable GROUP2 the item will be disabled. If you then enable GROUP1 again it will be enabled.

Parameter	Description	Required
Group Name	Name of the limits group	True

LIMITS_GROUP_ITEM

Adds the specified telemetry item to the last defined LIMITS_GROUP

Limits group information is typically kept in a separate configuration file in the config/TARGET/cmd_tlm folder named limits_groups.txt. If you want to configure multiple target items in a particular group you should put this information in the config/SYSTEM/cmd_tlm/limits_groups.txt file. The SYSTEM target is processed last and contains information that crosses target boundaries.

Parameter	Description	Required
Target Name	Name of the target Valid Values: Any Target Name	True
Packet Name	Name of the packet	True
Item Name	Name of the telemetry item to add to the group	True

Example Usage:

LIMITS_GROUP SUBSYSTEM
  LIMITS_GROUP_ITEM INST HEALTH_STATUS TEMP1
  LIMITS_GROUP_ITEM INST HEALTH_STATUS TEMP2
  LIMITS_GROUP_ITEM INST HEALTH_STATUS TEMP3

TELEMETRY Modifiers

The following keywords must follow a TELEMETRY keyword.

ITEM

Defines a telemetry item in the current telemetry packet

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Bit Offset	Bit offset into the telemetry packet of the Most Significant Bit of this item. May be negative to indicate on offset from the end of the packet. Always use a bit offset of 0 for derived item.	True
Bit Size	Bit size of this telemetry item. Zero or Negative values may be used to indicate that a string fills the packet up to the offset from the end of the packet specified by this value. If Bit Offset is 0 and Bit Size is 0 then this is a derived parameter and the Data Type must be set to ‘DERIVED’.	True
Data Type	Data Type of this telemetry item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
Description	Description for this telemetry item which must be enclosed with quotes	False
Endianness	Indicates if the item is to be interpreted in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

ITEM PKTID 112 16 UINT "Packet ID"
ITEM DATA 0 0 DERIVED "Derived data"

APPEND_ITEM

Defines a telemetry item in the current telemetry packet

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Bit Size	Bit size of this telemetry item. Zero or Negative values may be used to indicate that a string fills the packet up to the offset from the end of the packet specified by this value. If Bit Offset is 0 and Bit Size is 0 then this is a derived parameter and the Data Type must be set to ‘DERIVED’.	True
Data Type	Data Type of this telemetry item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
Description	Description for this telemetry item which must be enclosed with quotes	False
Endianness	Indicates if the item is to be interpreted in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

APPEND_ITEM PKTID 16 UINT "Packet ID"

ID_ITEM

Defines a telemetry item in the current telemetry packet. Note, packets defined without one or more ID_ITEMs are “catch-all” packets which will match all incoming data. Normally this is the job of the UNKNOWN packet.

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Bit Offset	Bit offset into the telemetry packet of the Most Significant Bit of this item. May be negative to indicate on offset from the end of the packet. Always use a bit offset of 0 for derived item.	True
Bit Size	Bit size of this telemetry item. Zero or Negative values may be used to indicate that a string fills the packet up to the offset from the end of the packet specified by this value. If Bit Offset is 0 and Bit Size is 0 then this is a derived parameter and the Data Type must be set to ‘DERIVED’.	True
Data Type	Data Type of this telemetry item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
ID Value	The value of this telemetry item that uniquely identifies this telemetry packet	True
Description	Description for this telemetry item which must be enclosed with quotes	False
Endianness	Indicates if the item is to be interpreted in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

ID_ITEM PKTID 112 16 UINT 1 "Packet ID which must be 1"

APPEND_ID_ITEM

Defines a telemetry item in the current telemetry packet

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Bit Size	Bit size of this telemetry item. Zero or Negative values may be used to indicate that a string fills the packet up to the offset from the end of the packet specified by this value. If Bit Offset is 0 and Bit Size is 0 then this is a derived parameter and the Data Type must be set to ‘DERIVED’.	True
Data Type	Data Type of this telemetry item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
ID Value	The value of this telemetry item that uniquely identifies this telemetry packet	True
Description	Description for this telemetry item which must be enclosed with quotes	False
Endianness	Indicates if the item is to be interpreted in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

APPEND_ID_ITEM PKTID 16 UINT 1 "Packet ID which must be 1"

ARRAY_ITEM

Defines a telemetry item in the current telemetry packet that is an array

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Bit Offset	Bit offset into the telemetry packet of the Most Significant Bit of this item. May be negative to indicate on offset from the end of the packet. Always use a bit offset of 0 for derived item.	True
Item Bit Size	Bit size of each array item	True
Item Data Type	Data Type of each array item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
Array Bit Size	Total Bit Size of the Array. Zero or Negative values may be used to indicate the array fills the packet up to the offset from the end of the packet specified by this value.	True
Description	Description which must be enclosed with quotes	False
Endianness	Indicates if the data is to be sent in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

ARRAY_ITEM ARRAY 64 32 FLOAT 320 "Array of 10 floats"

APPEND_ARRAY_ITEM

Defines a telemetry item in the current telemetry packet that is an array

Parameter	Description	Required
Name	Name of the telemety item. Must be unique within the packet.	True
Item Bit Size	Bit size of each array item	True
Item Data Type	Data Type of each array item Valid Values: INT, UINT, FLOAT, STRING, BLOCK, DERIVED	True
Array Bit Size	Total Bit Size of the Array. Zero or Negative values may be used to indicate the array fills the packet up to the offset from the end of the packet specified by this value.	True
Description	Description which must be enclosed with quotes	False
Endianness	Indicates if the data is to be sent in Big Endian or Little Endian format Valid Values: BIG_ENDIAN, LITTLE_ENDIAN	False

Example Usage:

APPEND_ARRAY_ITEM ARRAY 32 FLOAT 320 "Array of 10 floats"

SELECT_ITEM

Selects an existing telemetry item for editing

Parameter	Description	Required
Item	Name of the item to select for modification	True

Example Usage:

SELECT_TELEMETRY SYSTEM LIMITS_CHANGE
  SELECT_ITEM ITEM

DELETE_ITEM

(Since 4.4.1)

Delete an existing telemetry item from the packet definition

Deleting an item from the packet definition does not remove the defined space for that item. Thus unless you redefine a new item, there will be a “hole” in the packet where the data is not accessible. You can use SELECT_TELEMETRY and then ITEM to define a new item.

Parameter	Description	Required
Item	Name of the item to delete	True

Example Usage:

SELECT_TELEMETRY SYSTEM LIMITS_CHANGE
  DELETE_ITEM ITEM

Parameter	Description	Required
Meta Name	Name of the metadata to store	True
Meta Values	One or more values to be stored for this Meta Name	False

PROCESSOR

Defines a processor class that executes code every time a packet is received

Parameter	Description	Required
Processor Name	The name of the processor	True
Processor Class Filename	Name of the Ruby file which implements the processor. This file should be in the config/TARGET/lib directory so it can be found by COSMOS.	True
Processor Specific Options	Variable length number of options that will be passed to the class constructor.	False

Example Usage:

PROCESSOR TEMP1HIGH watermark_processor.rb TEMP1

ALLOW_SHORT

Process telemetry packets which are less than their defined length

Allows the telemetry packet to be received with a data portion that is smaller than the defined size without warnings. Any extra space in the packet will be filled in with zeros by COSMOS.

HIDDEN

Hides this telemetry packet from all the COSMOS tools

This packet will not appear in Packet Viewer, Telemetry Grapher and Handbook Creator. It also hides this telemetry from appearing in the Script Runner popup helper when writing scripts. The telemetry still exists in the system and can received and checked by scripts.

ITEM Modifiers

The following keywords must follow a ITEM keyword.

FORMAT_STRING

Adds printf style formatting

Parameter	Description	Required
Format	How to format using printf syntax. For example, ‘0x%0X’ will display the value in hex.	True

Example Usage:

FORMAT_STRING "0x%0X"

UNITS

Add displayed units

Parameter	Description	Required
Full Name	Full name of the units type, e.g. Celsius	True
Abbreviated	Abbreviation for the units, e.g. C	True

Example Usage:

UNITS Celsius C
UNITS Kilometers KM

DESCRIPTION

Override the defined description

Parameter	Description	Required
Value	The new description	True

Parameter	Description	Required
Meta Name	Name of the metadata to store	True
Meta Values	One or more values to be stored for this Meta Name	False

OVERLAP

(Since 4.4.1)

This item is allowed to overlap other items in the packet

If an item’s bit offset overlaps another item, COSMOS issues a warning. This keyword explicitly allows an item to overlap another and supresses the warning message.

STATE

Defines a key/value pair for the current item

Key value pairs allow for user friendly strings. For example, you might define states for ON = 1 and OFF = 0. This allows the word ON to be used rather than the number 1 when sending the telemetry item and allows for much greater clarity and less chance for user error.

Parameter	Description	Required
Key	The string state name	True
Value	The numerical state value	True
Color	The color the state should be displayed as Valid Values: GREEN, YELLOW, RED	False

Example Usage:

APPEND_ITEM ENABLE 32 UINT "Enable setting"
  STATE FALSE 0
  STATE TRUE 1
APPEND_ITEM STRING 1024 STRING "String"
  STATE "NOOP" "NOOP" GREEN
  STATE "ARM LASER" "ARM LASER" YELLOW
  STATE "FIRE LASER" "FIRE LASER" RED

READ_CONVERSION

Applies a conversion to the current telemetry item

Conversions are implemented in a custom Ruby file which should be located in the target’s lib folder and required by the target’s target.txt file (see REQUIRE). The class must require ‘cosmos/conversions/conversion’ and inherit from Conversion. It must implement the initialize method if it takes extra parameters and must always implement the call method. The conversion factor is applied to the raw value in the telemetry packet before it is displayed to the user. The user still has the ability to see the raw unconverted value in a details dialog.

Parameter	Description	Required
Class File Name	The file name which contains the Ruby class. The file name must be named after the class such that the class is a CamelCase version of the underscored file name. For example, ‘the_great_conversion.rb’ should contain ‘class TheGreatConversion’.	True
Parameter	Additional parameter values for the conversion which are passed to the class constructor.	False

Example Usage:

READ_CONVERSION the_great_conversion.rb 1000

Defined in the_great_conversion.rb:

require 'cosmos/conversions/conversion'
module Cosmos
  class TheGreatConversion < Conversion
    def initialize(multiplier)
      super()
      @multiplier = multiplier.to_f
    end
    def call(value, packet, buffer)
      return value * multiplier
    end
  end
end

POLY_READ_CONVERSION

Adds a polynomial conversion factor to the current telemetry item

The conversion factor is applied to raw value in the telemetry packet before it is displayed to the user. The user still has the ability to see the raw unconverted value in a details dialog.

Parameter	Description	Required
C0	Coefficient	True
Cx	Additional coefficient values for the conversion. Any order polynomial conversion may be used so the value of ‘x’ will vary with the order of the polynomial. Note that larger order polynomials take longer to process than shorter order polynomials, but are sometimes more accurate.	False

Example Usage:

POLY_READ_CONVERSION 10 0.5 0.25

SEG_POLY_READ_CONVERSION

Adds a segmented polynomial conversion factor to the current telemetry item

This conversion factor is applied to the raw value in the telemetry packet before it is displayed to the user. The user still has the ability to see the raw unconverted value in a details dialog.

Parameter	Description	Required
Lower Bound	Defines the lower bound of the range of values that this segmented polynomial applies to. Is ignored for the segment with the smallest lower bound.	True
C0	Coefficient	True
Cx	Additional coefficient values for the conversion. Any order polynomial conversion may be used so the value of ‘x’ will vary with the order of the polynomial. Note that larger order polynomials take longer to process than shorter order polynomials, but are sometimes more accurate.	False

Example Usage:

SEG_POLY_READ_CONVERSION 0 10 0.5 0.25 # Apply the conversion to all values < 50
SEG_POLY_READ_CONVERSION 50 11 0.5 0.275 # Apply the conversion to all values >= 50 and < 100
SEG_POLY_READ_CONVERSION 100 12 0.5 0.3 # Apply the conversion to all values >= 100

GENERIC_READ_CONVERSION_START

Start a generic read conversion

Adds a generic conversion function to the current telemetry item. This conversion factor is applied to the raw value in the telemetry packet before it is displayed to the user. The user still has the ability to see the raw unconverted value in a details dialog. The conversion is specified as ruby code that receives two implied parameters. ‘value’ which is the raw value being read and ‘packet’ which is a reference to the telemetry packet class (Note, referencing the packet as ‘myself’ is still supported for backwards compatibility). The last line of ruby code given should return the converted value. The GENERIC_READ_CONVERSION_END keyword specifies that all lines of ruby code for the conversion have been given.

Generic conversions are not a good long term solution. Consider creating a conversion class and using READ_CONVERSION instead. READ_CONVERSION is easier to debug and higher performance.

Parameter	Description	Required
Converted Type	Type of the converted value Valid Values: INT, UINT, FLOAT, STRING, BLOCK	False
Converted Bit Size	Bit size of converted value	False

Example Usage:

APPEND_ITEM ITEM1 32 UINT
  GENERIC_READ_CONVERSION_START
    value * 1.5  # Convert the value by a scale factor
  GENERIC_READ_CONVERSION_END

GENERIC_READ_CONVERSION_END

Complete a generic read conversion

LIMITS

Defines a set of limits for a telemetry item

If limits are violated a message is printed in the Command and Telemetry Server to indicate an item went out of limits. Other tools also use this information to update displays with different colored telemetry items or other useful information. The concept of “limits sets” is defined to allow for different limits values in different environments. For example, you might want tighter or looser limits on telemetry if your environment changes such as during thermal vacuum testing.

Parameter	Description	Required
Limits Set	Name of the limits set. If you have no unique limits sets use the keyword DEFAULT.	True
Persistence	Number of consecutive times the telemetry item must be within a different limits range before changing limits state.	True
Initial State	Whether limits monitoring for this telemetry item is initially enabled or disabled. Note if you have multiple LIMITS items they should all have the same initial state. Valid Values: ENABLED, DISABLED	True
Red Low Limit	If the telemetry value is less than or equal to this value a Red Low condition will be detected	True
Yellow Low Limit	If the telemetry value is less than or equal to this value, but greater than the Red Low Limit, a Yellow Low condition will be detected	True
Yellow High Limit	If the telemetry value is greater than or equal to this value, but less than the Red High Limit, a Yellow High condition will be detected	True
Red High Limit	If the telemetry value is greater than or equal to this value a Red High condition will be detected	True
Green Low Limit	Setting the Green Low and Green High limits defines an “operational limit” which is colored blue by COSMOS. This allows for a distinct desired operational range which is narrower than the green safety limit. If the telemetry value is greater than or equal to this value, but less than the Green High Limit, a Blue operational condition will be detected.	False
Green High Limit	Setting the Green Low and Green High limits defines an “operational limit” which is colored blue by COSMOS. This allows for a distinct desired operational range which is narrower than the green safety limit. If the telemetry value is less than or equal to this value, but greater than the Green Low Limit, a Blue operational condition will be detected.	False

Example Usage:

LIMITS DEFAULT 3 ENABLED -80.0 -70.0 60.0 80.0 -20.0 20.0
LIMITS TVAC 3 ENABLED -80.0 -30.0 30.0 80.0

LIMITS_RESPONSE

Defines a response class that is called when the limits state of the current item changes

Parameter	Description	Required
Response Class Filename	Name of the Ruby file which implements the limits response. This file should be in the config/TARGET/lib directory so it can be found by COSMOS.	True
Response Specific Options	Variable length number of options that will be passed to the class constructor	False

Example Usage:

LIMITS_RESPONSE example_limits_response.rb 10

Example File

Example File: <COSMOSPATH>/config/TARGET/cmd_tlm/tlm.txt

TELEMETRY TARGET HS BIG_ENDIAN "Health and Status for My Target"
ITEM CCSDSVER 0 3 UINT "CCSDS PACKET VERSION NUMBER (SEE CCSDS 133.0-B-1)"
ITEM CCSDSTYPE 3 1 UINT "CCSDS PACKET TYPE (COMMAND OR TELEMETRY)"
STATE TLM 0
STATE CMD 1
ITEM CCSDSSHF 4 1 UINT "CCSDS SECONDARY HEADER FLAG"
STATE FALSE 0
STATE TRUE 1
ID_ITEM CCSDSAPID 5 11 UINT 102 "CCSDS APPLICATION PROCESS ID"
ITEM CCSDSSEQFLAGS 16 2 UINT "CCSDS SEQUENCE FLAGS"
STATE FIRST 0
STATE CONT 1
STATE LAST 2
STATE NOGROUP 3
ITEM CCSDSSEQCNT 18 14 UINT "CCSDS PACKET SEQUENCE COUNT"
ITEM CCSDSLENGTH 32 16 UINT "CCSDS PACKET DATA LENGTH"
ITEM CCSDSDAY 48 16 UINT "DAYS SINCE EPOCH (JANUARY 1ST, 1958, MIDNIGHT)"
ITEM CCSDSMSOD 64 32 UINT "MILLISECONDS OF DAY (0 - 86399999)"
ITEM CCSDSUSOMS 96 16 UINT "MICROSECONDS OF MILLISECOND (0-999)"
ITEM ANGLEDEG 112 16 INT "Instrument Angle in Degrees"
POLY_READ_CONVERSION 0 57.295
ITEM MODE 128 8 UINT "Instrument Mode"
STATE NORMAL 0 GREEN
STATE DIAG 1 YELLOW
MACRO_APPEND_START 1 5
APPEND_ITEM SETTING 16 UINT "SETTING #x"
MACRO_APPEND_END
ITEM TIMESECONDS 0 0 DERIVED "DERIVED TIME SINCE EPOCH IN SECONDS"
GENERIC_READ_CONVERSION_START FLOAT 32
((packet.read('ccsdsday') * 86400.0) + (packet.read('ccsdsmsod') / 1000.0) + (packet.read('ccsdsusoms') / 1000000.0))
GENERIC_READ_CONVERSION_END
ITEM TIMEFORMATTED 0 0 DERIVED "DERIVED TIME SINCE EPOCH AS A FORMATTED STRING"
GENERIC_READ_CONVERSION_START STRING 216
time = Time.ccsds2mdy(packet.read('ccsdsday'), packet.read('ccsdsmsod'), packet.read('ccsdsusoms'))
sprintf('%04u/%02u/%02u %02u:%02u:%02u.%06u', time[0], time[1], time[2], time[3], time[4], time[5], time[6])
GENERIC_READ_CONVERSION_END

COSMOS

Telemetry Configuration

Telemetry Definition Files

TELEMETRY

SELECT_TELEMETRY

LIMITS_GROUP

LIMITS_GROUP_ITEM

TELEMETRY Modifiers

ITEM

APPEND_ITEM

ID_ITEM

APPEND_ID_ITEM

ARRAY_ITEM

APPEND_ARRAY_ITEM

SELECT_ITEM

DELETE_ITEM

META

PROCESSOR

ALLOW_SHORT

HIDDEN

ITEM Modifiers

FORMAT_STRING

UNITS

DESCRIPTION

META

OVERLAP

STATE

READ_CONVERSION

POLY_READ_CONVERSION

SEG_POLY_READ_CONVERSION

GENERIC_READ_CONVERSION_START

GENERIC_READ_CONVERSION_END

LIMITS

LIMITS_RESPONSE

Example File