The Allegro PCB Editor 16.6 ‘Show Measure’ command now displays results in database and alternate units. Alternate unit display requires the enablement of the user preference variable ‘showmeasure_altunits’. ‘Show Measure’ also supports a measurement between padstacks even if a common layer does not exist. This will be helpful when measuring mask-related geometry to conductor.Read on for more details …
Open the User Preference Editor as we need to enable the variable for dual units. Setup – User Preference Editor – Display – Element: Select an alternate unit of your choice; for example ‘millimeters’: Invoke Display – Measure or use the icon then make an adjustment to the find filter that aligns with your intended selection (pins, shapes, etc). Note the dual unit display in the report window: Measure two elements originating on different layers. For your convenience, there is a soldermask shape just below the Xhatch area: I look forward to your input on this new capability.Jerry “GenPart” Grzenia
While this is helpful, it's obviously used when the board file may not be designed in a desired unit. Or when the user is comfortable with multiple units (bi-unit-al??). In that case, it might be helpful to specify a pair of units which are always displayed. For example, if I choose MM and MIL, boards in MM show MIL as the alternate units and boards in MIL show MM as the alternate unit. For all the people involved in the PCB design/fabrication process, including supporting released PCBs, I can see a pair of units be helpful even if the units of the PCB design could be either of the units.
I have read with interest the article “What's Good About Allegro PCB Editor Show Measure for Dual Units?” written by Jerry Grzenia and I would like to say that I find this feature very helpful in the PCB development process because Allegro PCB Editor 16.6 offers a range of secondary units of measure, as centimeters, inches, and millimeters. The secondary conversion units are easily to be selected and are suitable for all datasheets, which display the dimensions only in the classical “Imperial” system (based on “inch” and “mil/thou”) or only in the “Metric” system (based on “millimeter”) or in both systems.
Starting with1988, the world standards organizations have started to agree that the metric unit system is superior for solving PCB design development. In the 1990’s, the components’ datasheets and the JEDEC component packaging dimensional datasheets, traditionally fully based on “Imperial”, where slowly converted to “Metric” (read the interesting article from the link: www.smtnet.com/.../The-Universal-PCB-Design-Grid-System.pdf). Another advantage of this “Dual Units” feature is seen during the PCB footprints (“PCB symbols” in Allegro/OrCAD) creation, because all the current datasheets present the dimensions, distances, diameters a.s.o. simultaneously in two units of measure (usually in “inch” and “millimeters”). On these terms, the dimensioning activity based on “Dual Units” is a necessary and useful feature of a modern PCB CAD system, offering a better flexibility during the design stage.
Finally, I would like to mention that another helpful feature is that the designer can measure distances between design objects from two different layers.
Thanks for your valuable comments and additional tips Norocel!