Ataytis Assurance · Reliability Block Diagram
Reliability block validation
The rules a reliability block diagram is checked against and their severity, and the messages they produce with how to fix them.
Rules
| Rule | Severity |
|---|---|
| A path runs from the input to the output | Error |
| Nothing leads into the input | Error |
| Nothing follows the output | Error |
| The m of an m-out-of-n block is a whole number of 1 or more | Error |
| m is no more than n | Error |
| No cycles, apart from dependencies | Error |
| At most one input and one output | Warning |
| Every block except the output leads somewhere | Warning |
| n matches the blocks connected to an m-out-of-n block | Warning |
| Node and relationship types are recognised | Warning |
| Every block is joined to the diagram | Warning |
None of these stops the diagram drawing. A missing Node ID mapping does. A reliability block diagram has no advisories.
Messages and fixes
| Message | Fix |
|---|---|
| No complete path connects the input side to the output side. | Check Connected Node ID along the path. If the input and output are reported as well, the table names the previous block: change Reads as on the Data Mapping tab. |
| An input is where the diagram starts, so nothing may lead into it. Remove the incoming connection, or make this a component. | Remove the row that leads into the input, or change its Node Type. |
| An output is where the diagram stops, but this one carries on into another block. Remove the onward connection, or make this a component if the path continues past it. | Clear Connected Node ID on the output's row. |
| Nothing leaves this block, so no path through it reaches the output. Connect it onward, or make it the output if the diagram ends here. | Give the block a Connected Node ID, or make it the Output. |
| An m-out-of-n block needs at least one of its inputs, and this one asks for 0. | Set Vote Threshold to a whole number of 1 or more. |
| This block asks for 4 of 3 inputs, which can never be met. The number required cannot exceed the number available. | Correct Vote Threshold or Vote Input Count. |
| This block says it has 3 inputs, but 2 are connected to it. Correct the count, or connect the blocks it is missing. | Correct Vote Input Count, or connect the missing blocks. |
| Input occurs 2 times. | Keep one input. A second output gives the same message for Output. |
| The graph contains a directed cycle that is invalid for this mode. | A block leads back to one before it. Check Connected Node ID, or use a Dependency where one block affects another. |
| A relationship references a node that is not present. | A Connected Node ID names a block with no row of its own. Add its row, or correct the identifier. One that differs only by spaces is named in the message. |
| The diagram contains 2 disconnected components. | Some blocks are not joined to the rest. Check Connected Node ID. |
An unrecognised node or connection type is reported as, for example, "Pump" is not a recognised node type. Map the value under Node type values or Relationship values on the Data Mapping tab. Names and numbers in all these messages come from your data.