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Basic MIL-STD-1553B questions

Greetings,

I don't know if I'm in the right place for this, but I am looking to get some basic questions answered about the MIL-STD-1553B bus architecture. I'm currently researching this as part of a task I'm doing for work. Here are my initial questions:

  1. Can a BC send messages to itself?
  2. Why do status words get suppressed in Broadcast Mode? Why *can't* RTs "flood" the bus in the manner of nodes on an Ethernet network?
  3. Are 1553B buses inherently redundant, or do hardware and software manufacturers have to have a second physical bus, etc.?
  4. Are there naturally two channels per 1553B, or is that a redundancy implemented by manufacturers?

I'm sure I'll have a lot more questions but I'll start with these. Thanks in advance for any help you can provide.

Mike

Reply to
Zerex71
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In a nutshell:

  1. No - it doesn't have an RT address
  2. The bus cannot handle simultaneous transmissions. Determinism is the key requirement and this would violate it.
  3. No
  4. No, it's a manufacturer thing. Recommended in the handbook but not part of the standard.

Regards,

Rog.

Reply to
Roger

Not normally. Some chipsets allow you to configure the chip as an RT and a monitor for test purposes or to enable loopback for testing. But in general, no.

Because that is what the standard says :). In truth, 1553 is a very very simple protocol and coming up with a plan for who would talk when for a broadcast would add a lot of complexity. I

RTs are not allowed to say anything at all unless spoken to and then are limited to transmitting 32 data words (plus the status word). So, the definition of the protocol prevents "flooding". Obviously a defective RT could violate the protocol.

1553 is a command response protocol. RTs never get to "transmit" anything on their own. They simply put data in a "subaddress" and hope that the BC will come along and ask for it.
1553B is physically redundant. (I believe A was not). So, there is is always another set of wires for the second channel. There is some software needed to make it work. Usually just for the bus controller, the standard does not really say how and when the BC should select between the two buses.

I think this has already been covered.

Reply to
Jeffrey Creem

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