Example of CCSDS packet generation

[gabrielesartor]

Hi everyone,
I'm not familiar with the space standard packets and I'm trying to create messages using CCSDS format and I've found this library which seems really good for it.
Anyway, I don't really understand how to put my data inside a telemetry packet. Does anyone have an example of creation of a message including his data?
For instance I'm tring to create a CCSDS package in this way:

from CCSDS import PACKET
packet = PACKET.createIdlePacket()

However, I don't understand how to insert my data, for instance "latitude":10.4444, "longitude":xxx, "yaw":xxx etc.
Can anyone share a simple example of it using this library?
Thank you in advance

[Stefan-Korner]

There are several ways to set the data in the packet, two of them are shown here:

Example 1: Simple example

import CCSDS.PACKET
# create the packet - contains only the CCSDS packet header
packet = CCSDS.PACKET.Packet()
print(packet.getDumpString())
# set the total size of the packet: 20 bytes
packet.setLen(20)
print(packet.getDumpString())
# set some field in the packet: see UTIL.DU
packet.setFloat(8, 4, 10.4444)
packet.setUnsigned(12, 2, 65535)
packet.setString(14, 4, "test")
print(packet.getDumpString())
# set the packet header: see CCSDS.PACKET
packet.applicationProcessId = 1234
packet.sequenceControlCount = 5678
packet.setPacketLength()
print(packet)
# set a CRC (if needed)
packet.setChecksum()
print(packet)

Example 2: set packet from layout template

import CCSDS.PACKET
import UTIL.DU
# prepare the layout template: data are placed after the CCSDS packet header
USER_DATA_BYTE_SIZE = 14
USER_DATA_ATTRIBUTES = {
  "latitude":  (2, 4, UTIL.DU.FLOAT),
  "longitude": (6, 2, UTIL.DU.UNSIGNED),
  "yaw":       (8, 4, UTIL.DU.STRING)}
# create the packet according to the layout template
packet2 = CCSDS.PACKET.TMpacket(attributesSize2=USER_DATA_BYTE_SIZE,
                                attributeMap2=USER_DATA_ATTRIBUTES)
print(packet2)
# set some field in the packet
packet2.latitude = 10.4444
packet2.longitude = 65535
packet2.yaw = "test"
print(packet2.getDumpString())
# set the packet header: see CCSDS.PACKET
packet2.applicationProcessId = 1234
packet2.sequenceControlCount = 5678
packet2.setPacketLength()
print(packet2)
# set a CRC (if needed)
packet2.setChecksum()
print(packet2)

[gabrielesartor]

Thank you Stefan, it seems working well!