I've got a device that the manufacturer claims uses a 3.81mm pitch connector. I measured the actual distance between pins, and it appears to be 3.5. I'm now noticing that some connector manufacturers refer to a "3.5/3.81" connector. I obviously don't want to buy the wrong one. If a connector is listed as "3.81mm pitch", is that the same as a 3.5/3.81mm connector? If it matters, I need these connectors for an NI-USB-6001 DAQ
3.5 is obviously not the same as 3.81, and anything with more than about 2 pins is not going to fit, even if you force it on. Some manufacturers make series which are similar in size (eg. 5mm/5.08mm pitch) and combine the two in their literature because the construction is very similar between the two. When you drill down to the part numbers, they will be different for the two pitches.
I happen have a NI 6216 (different model but the same series) in front of me and the pitch is definitely 3.81mm (0.15") for the 16 pins/15 spaces. It also has mounting ears with captive screws and customized markings.
If you buy NI's terminal blocks you get whatever customization they do, the correct part, and a nifty screwdriver. For a price.
similar-looking pluggable connectors are available in both 3.5 and 3.81, be sure you choose the right pitch.
Choosing the right manufacturer is less of an issue. parts from different manufacurrers all seem to be interchangable (so long as you don'r exceed the manufacturers ratings)
this photo taken from a vendor who sells both 3.81 and 3.5mm pitch connectors