I've got a schematic that has been through several revisions, and I noticed when generating my BOM that the most recent two revisions are now generating an error in Reports > Bill of Materials tool. For some reason some components are being double counted. Like a resistor that is only used once, is showing as a quantity of 2 in the generated BOM?

Has anyone ever run into this with Altium? The schematic two revisions ago, correctly counts the quantities but I evidently did something that upset Altium...

  • \$\begingroup\$ What are the part numbers in the BOM doing? \$\endgroup\$ Sep 14, 2017 at 14:52
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    \$\begingroup\$ Does the BOM list 2 separate designators for that resistor? \$\endgroup\$
    – Steve G
    Sep 14, 2017 at 14:53
  • \$\begingroup\$ Okay, so here is a clue... when I remove the schematic from the project, and open it as as free document, the BOM report is correct... The part has only one designator, and the part number is unique. I think the problem is that I have two .SchDocs open in the project (each revision of the schematic) so it is double counting each designator (as the schematics share the designators). I would have assumed the BOM tool treats each .SchDoc as a seperate entity -- guess not. I just saved myself from ordering an extra 500,000 passive components... \$\endgroup\$
    – Leroy105
    Sep 14, 2017 at 14:58
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    \$\begingroup\$ You should keep different schematic revisions in their own respective projects. \$\endgroup\$
    – DerStrom8
    Sep 14, 2017 at 15:44
  • \$\begingroup\$ @DerStrom8 -- what I really should do is just use SVN for version control. I use git for software, but am still doing ghetto manual version control for Altium. I just upgraded to using outjobs instead of manually clicking around. \$\endgroup\$
    – Leroy105
    Sep 14, 2017 at 17:21

1 Answer 1


A second menu is provided from which you can specify the data source that is to be used when the BOM report is generated.

Only pick the applicable data source.

  • \$\begingroup\$ Excellent, I will check that. I just kind of speed through that BOM report tool. Thank you. \$\endgroup\$
    – Leroy105
    Sep 14, 2017 at 15:09

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