Ping John Larkin: Question on MAX
in [Design]
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From: langwadt on 28 May 2010 16:28 On 28 Maj, 21:55, "Joel Koltner" <zapwireDASHgro...(a)yahoo.com> wrote: > "Nico Coesel" <n...(a)puntnl.niks> wrote in message > > news:4c001d6f.880956593(a)news.planet.nl... > > > "Joel Koltner" <zapwireDASHgro...(a)yahoo.com> wrote: > >>Since RLCs, etc. already encode their "primary value" (e.g., resistance for > >>resistors, capacitance for capacitors, etc.) into the internal part number, > >>we've kicked around the idea of buliding a little program that takes a > >>"template" part number from the (in our case) ORCAD-generated BOM, and > > If you use/switch to Orcad CIS it does all the work for you. > > We have ORCAD CIS and no, it doesn't, AIUI: If you want to change, e.g., a > resistor's value only (but it's still the same old 0603 generic resistor > otherwise), you can to use "change database part" and go find the new, e.g., > 1.12k, 0603 resistor. In most cases that's a lot more mouse clicks that > double-clicking one on the part's value, entering the new value, and calling > it good. > > Another benefit is that you're not immediately stuck if no one's gotten around > to entering 1.12k 0603 resistors into the master part database in the first > place (whereas they did already have, e.g., 2.22k in there, what you initially > used). ...so you call or e-mail the guy maintaining the parts database, ask > him to add the part, and then come back after lunch and continue updating a > schematic. > > Both of these things are productivity killers, in my mind. > > But if I'm wrong about ORCAD CIS's capabilities here, I'd appreciate being > told as much. > been I while since I've used orcad, but I think you can just change the value, and it'll then be flagged as not tied to the database something that can be fixed later when you are preparing for production. being tied to the database has the advantage that you can choose components you already have -Lasse
From: Joel Koltner on 28 May 2010 16:35 <langwadt(a)fonz.dk> wrote in message news:c9126b32-ff3c-4409-93d7-8257635658d3(a)e28g2000vbd.googlegroups.com... >been I while since I've used orcad, but I think you can just change >the value, >and it'll then be flagged as not tied to the database something that >can be fixed >later when you are preparing for production. I expect you're correct, although it sure seems to me that not having a "fixing" step (except for where parts don't exist in the database yet) is desirable. "being tied to the database has the advantage that you can choose components you already have" In general I agree, but we generally assume that any, e.g., E96 1% 0603 resistor is available inexpensively and overnight (if necessary) from the likes of DigiKey, so we generally don't keep stock of a particular value until it's actually being used in production somewhere. (We do have engineering kits with every single value stocked -- for prototypes the production guys will occasionally grab some of these, which is fine.) ---Joel
From: John Larkin on 28 May 2010 16:46 On Fri, 28 May 2010 11:52:49 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >Thanks John, that's good information. > >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:5g1006p4tn9geie0k1s12acg3j2o02f6bs(a)4ax.com... >> My weekend project is to write a PowerBasic program that verifies >> that, on a schematic, all the r/c/l values in the "value" field are >> consistant with the values of the MAX part. I'll do that based on an >> ascii schematic dump and an ascii MAX parts listing, which is easier >> than messing with binaries. PB is so fast that the most brutal linear >> searches are fine. We need that program because certain engineers, who >> I will not name, keep changing parts values before the board is >> finished, and The Brat gets annoyed keeping up with, and checking, the >> results. > >Since RLCs, etc. already encode their "primary value" (e.g., resistance for >resistors, capacitance for capacitors, etc.) into the internal part number, >we've kicked around the idea of buliding a little program that takes a >"template" part number from the (in our case) ORCAD-generated BOM, and >combines it with the "value" attribute in the schematic to then generic the >"fully qualified" internal part number. This idea was meant specifically to >avoid the problem you're describing -- engineers can change values all day >long, and you still end up with valid internal part numbers. (Granted, some >of those parts numbers might not exist yet within the MRP system, if we've >never used, e.g., a particular 1% resistor value before -- but that can be >checked as well, and a report generated that tells purchasing to buy >some/create the part/etc.) Yeah, that would be better. Our MAX numbers also encode value. But more work, and still could leave holes for tolerance, t/c, things like that, or parts that aren't actually in stock. If I just check the "value" field against the value from our stock listing, that will catch most errors and maintain family harmony. A new rule is that if an engineer owns a schematic and changes a value, he wipes out the MAX field to note the change. So The Brat can fill it in, or else it becomes a TBD, which attracts attention. My checker thing will help. How do you program stuff like this? Is it easy to get at the ORCAD library? PADS includes some VisualBasic scripting thingie, but we've never used it. Our parts lists are simple... 22A450.1A \ ASSY, PCB, V450 ANALOG INPUT \ 08-DEC-05 \ R GADDI 104-2160 2 C69 C73 105-2301 16 C13 C28 C44 C58 C74 + C90 C105 C122 C141 C157 + C175 C193 C208 C222 C236 + C253 105-2001 16 C7 C22 C37 C52 C66 + C84 C98 C115 C135 C150 + C165 C185 C202 C216 C230 + C245 116-3381 3 C191 C282 C285 103-3080 32 C3 C9 C18 C24 C34 + C39 C49 C54 C63 C68 + C79 C86 C95 C100 C110 + C117 C127 C137 C146 C153 + C162 C167 C180 C187 C199 + C204 C213 C218 C227 C232 + C242 C247 and like that. A part entry is @123-4567 if it's a subassembly to be broken down. John
From: langwadt on 28 May 2010 17:04 On 28 Maj, 22:35, "Joel Koltner" <zapwireDASHgro...(a)yahoo.com> wrote: > <langw...(a)fonz.dk> wrote in message > > news:c9126b32-ff3c-4409-93d7-8257635658d3(a)e28g2000vbd.googlegroups.com... > > >been I while since I've used orcad, but I think you can just change > >the value, > >and it'll then be flagged as not tied to the database something that > >can be fixed > >later when you are preparing for production. > > I expect you're correct, although it sure seems to me that not having a > "fixing" step (except for where parts don't exist in the database yet) is > desirable. still need to check everything is ready for layout, maybe add mechanic stuff etc. > > "being tied to the database has the advantage that you can choose > components you already have" > > In general I agree, but we generally assume that any, e.g., E96 1% 0603 > resistor is available inexpensively and overnight (if necessary) from the > likes of DigiKey, so we generally don't keep stock of a particular value until > it's actually being used in production somewhere. (We do have engineering > kits with every single value stocked -- for prototypes the production guys > will occasionally grab some of these, which is fine.) > > ---Joel sure for cheap generic stuff like that it doesn't matter much, but if you need a .50$ 25ppm melf resistor it makes sense to pick the value you already have a reel off from last time, if you can -Lasse
From: Joel Koltner on 28 May 2010 17:48
<langwadt(a)fonz.dk> wrote in message news:07530863-1451-4797-8909-a426253aa079(a)a16g2000vbr.googlegroups.com... On 28 Maj, 22:35, "Joel Koltner" <zapwireDASHgro...(a)yahoo.com> wrote: >> "being tied to the database has the advantage that you can choose >> components you already have" >> In general I agree, but we generally assume that any, e.g., E96 1% 0603 >> resistor is available inexpensively and overnight (if necessary) from the >> likes of DigiKey, so we generally don't keep stock of a particular value >> until >> it's actually being used in production somewhere. >sure for cheap generic stuff like that it doesn't matter much, but if >you need >a .50$ 25ppm melf resistor it makes sense to pick the value you >already have a >reel off from last time, if you can Yes, you have to effectively trust the engineer to know what a "generic" part is and what isn't. (One can just make a list somewehre...) Logistically, since an internal part number *might* map to multiple manufacturer part numbers (that are all considered form, fit, and function compatible), you just use one internal part number for "generic" components (e.g., for resistors where you only care about resistance, tolerance, and footprint) and other internal part numbers for a specific manufacturer's part (and the idea is that no one will substitute this part on you within an ECO or similar). It would be nice if ORCAD CIS would let you lock attribute fields on placed parts so that you don't run into the whole "engineer changed the component value but not the internal part number" problem in the first place (...for non-generic parts). Maybe it does? I just don't know yet. (We had discussed other options such as the generic parts having a slightly different symbol or differently colored attributes to make it obvious to the casual observer which parts are generic and which shouldn't have any attributes changed without fixing the internal part number.) ---Joel |