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ganesh1950
09-05-2008, 12:46 PM
Anyone who has had experience with RS-485, I would request recommendations for make and model of "genuine" rs-485 interface chips availability in India for hobby application in less than 6 numbers quantity.
ganesh1950

ganesh1950
09-06-2008, 02:12 PM
The final application is to be a multiple micro-controller robot in an harsh environment. As I had some problems with dubious rs232 chips in the market, hence I wanted to seek guidance about genuine rs485 chips, before starting to use them, as most of my sources were not familiar in using rs485.

Any help would be most welcome.

Am I addressing this in the wrong forum ? Moderator please ?

ganesh1950

wizardjack
09-06-2008, 04:13 PM
I had used National Semiconductors DS485 (RS485/RS422 multipoint Transceiver) few years back for multidrop communication.

I think it should be available in market. Checkout OM electronics, Vishal electronics at SP Road B'lore.

btw what do you mean by "dubious rs232 chips" ? which chips did you use ?

cheers!!!

MohitM
09-07-2008, 12:25 AM
See MAX485.

rao
09-07-2008, 03:44 AM
right forum..

Rao

ganesh1950
09-11-2008, 08:07 PM
I had used National Semiconductors DS485 ......
btw what do you mean by "dubious rs232 chips" ? which chips did you use ?
cheers!!!

Thanks wizardjack, sometimes the market gets dumped with components which have been rejected by some bulk buyer for some defect which appear only under specific conditions. The end seller may or may not be aware as they are just traders. Only when you start using these components to their fullest specs they start misbehaving and difficult to identify when you are in a new project if it is our hardware design, our software design or the component problem, this takes a great deal of effort and time to identify. Some time back some batches of MAX232 for RS232 application, I had such problems.

Ganesh1950

docel
09-12-2008, 10:27 AM
ICs dont come to the market like that. It is wrong to assume such things.
There may be any number of end-user reasons for their failure. These subtle reasons will automatically and unknowingly get corrected, after every failure, without your knowledge.
Besides, there are different suffixes. These have different characteristics altogether, and the Datasheets are the only way of knowing this. Failing to refer will result in the ICs misbehaving or failure.

The only way to confirm a bad manuf/ defect is to plug in the ICs sequentially without disturbing or making any changes to the test circuit.

There are stringent QC and QA procedures in vogue at the Manufacturers' and bad ICs cannot come into the market.

A Lot of times, the ICs will just die before plugging them in, as soon as you 'touch' them. But it doesnt happen with the MAX232.

ganesh1950
09-17-2008, 04:07 PM
I humbly respect Docel's statements and agree that is how it should normally be. Manufacturers do take suitable actions. I DO NOT want to start any flame / war. But there are genuine problems or duplicates (definition is difficult). Just a few case references :-

https://www.lawyersandsettlements.com/case/defective_camera_chip_california

http://findarticles.com/p/articles/mi_m0EKF/is_47_45/ai_57770284

http://www.wired.com/techbiz/media/news/2005/03/66928

http://www.circuitnet.com/articles/article_49561.shtml

http://news.cnet.com/2100-1001-269748.html

http://findarticles.com/p/articles/mi_m0EIN/is_2000_March_20/ai_60478875

http://www.engadget.com/2005/01/05/defective-amd-cpus-on-sale/

http://forums.freescale.com/freescale/board/message?board.id=FORUMUSE&message.id=350

Please I once again humbly mention that my first and second email clearly DID NOT convey anything wrong; but asked for genuine parts suppliers. But it was only on the request of another member what I had experienced, this one episode which did take place and we did get a confirmation from the original manufacturer that the concerned chip was a duplicate was mentioned in the forum. However I do not want to take up further on this issue.

But if this has hurt the feelings of the forum, I openly oppologise and will not
mention such issues in future in this forum.

ganesh1950