RS485 questions

The continued unavailability of the SN75176 chip is keeping me from completing my electonics, so I started looking for a replacement part. I found a Sparkfun SP3485 breakout board, and I thought I might be able to use it to provide communications for my protoboard Extruder Controller, but then I noticed that the chip is wired differently, with /RE tied to DE. When I compared this to the Motherboard and Extruder Controller schematics, and reviewed the SN75176 and SP3485 datasheets, I got confused. Why is /RE tied high??? Wouldn't that disable the chip? And has anyone else successfully substituted an SP3485 for the SN75176 chip?

eustace,

What country are you in? In the US, digikey seems to show no shortages, under a buck/part in quantity 1.
[search.digikey.com]

If you're in a bind on this, send me a PM and I'll see if I can help you out.

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Larry Pfeffer,

My blog about building repstrap Cerberus:
[repstrap-cerberus.blogspot.com]

Oops!
I see that the soic package is out of stock at digikey,
but mouser has some in stock in soic-8:
[mouser.com]

Or you could still buy a DIP8 version,
(digikey shows over 10K in stock): [search.digikey.com]

put it on some perfboard, and tack on wires to connect. Tedious, but probably faster than revising the ckt to use a different chip.

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Larry Pfeffer,

My blog about building repstrap Cerberus:
[repstrap-cerberus.blogspot.com]

For a while, there, neither had the soic part. I'm ordering a dip part for the protoboard extruder controller. My confusion over the pinout was just self-inflicted - I needed to take a closer look at the schematic.
But the breakout board SP3485 came in handy. It really is a drop-in replacement if you have a 5V circuit (or so I'm told) so I removed it from the breakout board and put it on my motherboard, which is now complete and functional.