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RS232 - RS 485 converter

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proton

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75176 application note

Hi friends,
I need to connect two PIC using USART, but considering the long distance, I think I'll
need to convert rs232 to rs485 and then back
to rs 232. Does someone has suggestions, esperience about the solutions I should use ?
thx
proton
 

Hollaender

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75sn176

If you don't have a problem with a 4-wire connection I think you should consider RS-422 as this will allow you to operate full duplex without having to switch the hardware from receiving to transmitting all the time....
Furthermore termination is important when the distance is getting longer. Texas Instruments has some nice app-notes about this issue
 

johnyaya

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75176 rs232

with rs485 each node can become the bus master vs. rs422 where only one is master, thus making coding easier, just depends on your needs. rs485 and rs422 have the same specs otherwise if memory serves me correctly, yes?
 

ljmnunes

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isolated rs485 schematic

Hi, Proton!

I have a schematic of a RS232-485 converter.
I always used without troubles.

It is in PCad 2002 format.

Good luck

Laercio
 

ljmnunes

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rs232 rs485 converter schematic

For some reason the extension of the file was changed.
You must to change back to .SCH, ok?

good luck
 

somkiatss

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rs485 opto isolated schematic

Hi proton,
I think that no need to convert RS232 to 485
you can use RS 485 direct to your PIC very easy you can find RS 485 driver IC#75176
which you can upgrade to RS 422 due to 422 is
full duplex point to point but 485 is half duplex
SomkiatSS
 
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Slammer

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sn75176 application note

SomkiatSS you have right,
we can use directly the old SN75176 or some improved devices like ADM483 from AD, or MAX483 (I think), or some chips from Sipex.

Keep in mind, that these chips are not isolated. The Network must be short and to have good grounding.

The TOTAL solution is the MAX1480 (Isolated RS 485 tranceiver in one chip) but a bit expensive.

Slammer
 

Trishool

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atmega8 rs485

Hi proton try this link and grab the schematics ###.rs485.com .

Greetz.........
 

mcu_dev

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75176 rs485

Hi Proton. You can find more info. at google.com with keyword rs485. it very good
 

arcaphill

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rs 232485 serial connector pin diagram

Visit Maxim, TI, or Fairchild web for it!
 

walt

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rs485 app note pic

Need some help!
Have made working bidirectional rs485 interface with sn75176, optocouples
PC - atmega8, rate 9600.
Replaced it by max1480B, but can send data only to atmega8.
PC receives corrupted data.
Tried to make some delays after switching direction, but no results.
What's the matter?
 

yangxh

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rs 485 rs 232 converter wiring diagram

HI,ljmnunes
I can't link your source file.
can you correct it?
 

7rots51

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sn75176 application

hi
Do not use 75sn176 because its design is return to many years ago,it is not siutable for new designs and have not any protection(for ex. at best case 2kv ESD )at RS485 bus level,use new parts that support 256,128 nodes and high ESD protection and ..... like SN65LBC184 ( industerial temperature range with internal TVS)
 

ljmnunes

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sn75176 application note rs 485

yangxh said:
HI,ljmnunes
I can't link your source file.
can you correct it?
Sorry...

I know that I'm too late to post a reply, but I'm upload the schamatic in a pdf format.

May be it is helpfull...

[]s
 

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Justins

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ftdi rs485 schematic isolated

offering a device:

Features:

Enables full duplex data transmitting with galvanic unbinding between supported interfaces: RS-232, RS-485, RS-422
Full/half duplex option
Data transmitting rate up to 19,2 kbps
It is possible to increase the noise resistance of the data transmitting
Power supply voltage (9...24)V


> Connect your RS-485 or RS-422 equipment in a simple and safe way to the RS-232 standard interface.

> Increase the length of the RS-232 data transmitting lines, for more than kilometer, by using two converters.

> It is possible to have two options: with optical unbinding and without
 

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