Req. 5.2.2.1.1: "Command, Telemetry, and Data Bus Protocol - SC"

The SIU FSW shall exchange commands, low rate telemetry, time messages, and ancillary data with the SC C&DH across a MIL-STD-1553B bus, using the MIL-STD-1553B physical layer protocol.

Basis (help)

[2] (3.2.5.1.1), [3] (5.3.4), [4] (5.3.1)

2: "LAT Instrument - Spacecraft Interface Requirements Doc." (NASA 433-IRD-0001)

3.2.5.1.1: "CTDB Specification"

Commands, telemetry, time messages, and ancillary data shall be transferred between the LAT and the SC via a serial CTDB compliant with MIL-STD-1553B.

3: "LAT Performance Spec. - Level II(b) Spec." (LAT-SS-00010)

5.3.4: "Data Services {SI/SC IRD 3.2.5}"

The SI shall communicate with the spacecraft via a serial command, telemetry, and data (CTDB) bus as defined by MIL-STD-1553B as specified in the SI/SC IRD.

The communications shall include SI housekeeping data, PPS time mark signal, time distribution, analog monitoring signals, discrete control signals, configuration commands, memory and table loads, real-time pointing commands, instrument mode settings, and transient event reporting/repointing.

4: "LAT T&DF Subsystem Spec. - Level III Spec." (LAT-SS-00019)

5.3.1: "Spacecraft Commanding Interface"

The control system shall accept control commands and data from the spacecraft as specified in the Spacecraft Interface Requirement document, 433-IRD-0001.

Context (help)

Test(s)

001: 1553 Interface Test

This test shall first verify the electrical characteristics of the LAT 1553 interface, then demonstrate (in conjunction with a spacecraft simulator) that the LAT can exist on the bus without responding to messages directed to other remote terminals. Next, processing of telemetry requests shall be demonstrated, followed by exercising the command interface to the LAT and verifying that all commands and command data are correctly interpreted. Commands need not be executed to successfully carry out this test. Timing measurements for the standard message traffic shall also be performed.