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The Virtual Spacecraft (VSC)
Chapter 3 Using the proxy interface
Users Manual
Version/Issue: 1.4/2
through the VSC ’s 850 and 468 boards (see Chapter 2). Once brought to the VSC these data are
digitized by the VSC ’s Systran boards (see Chapter 2). The monitor software on the VSC
periodically, once a second, reads these digitized temperatures and voltages, packages them
up as a set of CCSDS telemetry packets and sends these packets down to the proxy through its
VSC diagnostic stream (see Section 7.2). The monitor has two components: the primary monitor
and the redundant monitor. The user must select which one of these two monitors will be used
to collect this telemetry. Once this telemetry arrives at the proxy, the user handles this
information in the same fashion as it would process any other telemetry (see Section 3.4).
Monitor selection (primary or redundant) as well as its disabling is available through the
proxy interface (see Section 7.10). When monitoring is disabled, the VSC no longer either
acquires or transmits monitoring packets.
The VSC specifies one APID for the information digitized by the 850 board and one APID for
the information digitized by the 468 board. Therefore, once a second, the user can expect to
see two different packets on the diagnostic stream. The structure and APIDs of these packets
are defined in Appendix B. Note that the telemetry packet contains a field identifying whether
data were acquired with the primary or redundant monitor. Different versions of the VSC can
contain, zero, one, or both of these boards, consequently, the actual number of packets
transmitted per second is dependent on the number of boards. For example, if a VSC contains
only an 850 board, only the packet corresponding to that board is transmitted. If the VSC
contains neither of these boards, nothing will be transmitted. In short, to acquire and process
diagnostic telemetry from the proxy requires:
—
at least one of either an 850 or 468 board
—
the corresponding Systran boards
—
cabling correctly established between LAT and VSC (and potentially a BPU )
—
router and handler connected to VSC diagnostic stream
—
monitoring to be enabled
In order to enable or disable monitoring one instantiates the Monitor class (see Section 7.10).
The argument to its constructor is an enumeration specifying which of two monitors to
enable. For example, to enable monitoring from the Primary monitor:
vsc.execute(Monitoring(Primary));
and to disable monitoring...
vsc.execute(Monitoring(None));
Finally, to enable monitoring from the Redundant monitor:
Initial public release
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