[sci.electronics] Current-loop rs-232 <-> rs-232 converter scematics needed

huopio@lut.fi (Kauto Huopio OH5LFM) (08/31/90)

If anyone has easy scematics for a converter from current-loop rs-232
to "normal" rs-232, please e-mail here. Our cs club got a printer that
works on current-loop rs-232 and our HP 9000/550 speaks just normal
rs-232.. I guess that there is a chip that does it all :-?

--kauto

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****************** Kauto Huopio (huopio@kannel.lut.fi) **********************
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wayned@wddami.spoami.com (Wayne Diener) (09/02/90)

>In article <HUOPIO.90Aug31115619@kannel.lut.fi> huopio@lut.fi (Kauto Huopio OH5LFM) writes:
>If anyone has easy scematics for a converter from current-loop rs-232
>to "normal" rs-232, please e-mail here. Our cs club got a printer that

I've used the following circuit successfully.  I'm not aware of any 
IC's that do it directly ---

   Current Loop Side                               Logic Side

                                              +5
                                              ___
                                               | 
                    4N28          +5           R 
                   --------       ___          R  2.2K    RS232 driver (inverting)
                1  |      | 6      |           R        |\
   + (source) -----|      |---------           |--------| o----->
                2  |      | 5     10K        |/ C       |/
   - (sink)   -----|      |------RRRRR-------|   2N222
                3  |      | 4                |\ E  
       No Conn. ---|      |------RRRRRR---|----|
                   --------       180K    |
                                         ---
                                         \ / (gnd)

 
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