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???
08/03/11 18:01
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#183181 - probably
Responding to: ???'s previous message
...monovibrator is used to produce 'Drive enable' signal for 485 transceiver chip ( pulse with one byte length, restarted by any passive to active level edge) - i suppose there is not used any additional signal from RS232 side - so converter is transparent for software (only TX,Rx and Gnd used).

In this case schematic is highly desirable for right suggestions.
There are 3 scenarios may be:
- Tx input of converter is high impedance (>10 kiloohm) , in this case 1 kiloohm resistor is ok;
- Tx input of converter is something like MAX232 with input about 3 kiloohm , in this case recomended value is about 2 kiloohm ;
- Tx input is low impedance ( but not optron) , i think best solution is to change converter;

Anyway - schematic is needed.

regards


List of 29 messages in thread
TopicAuthorDate
Problem with RS232/RS485 converter...            01/01/70 00:00      
   More info please            01/01/70 00:00      
      probably            01/01/70 00:00      
   more info...            01/01/70 00:00      
      yes,i think            01/01/70 00:00      
         input impedance            01/01/70 00:00      
            i'm wrong            01/01/70 00:00      
               what is the right value?            01/01/70 00:00      
                  did You tryed capacitor?            01/01/70 00:00      
                     thanks...            01/01/70 00:00      
                     it works...!            01/01/70 00:00      
                        congrats            01/01/70 00:00      
                           shape            01/01/70 00:00      
                              dont            01/01/70 00:00      
                                 It is OK.            01/01/70 00:00      
   Hints...            01/01/70 00:00      
      schema            01/01/70 00:00      
         Repair...            01/01/70 00:00      
            transils...            01/01/70 00:00      
               RS485            01/01/70 00:00      
                  Sample Schematic            01/01/70 00:00      
                     Thank you very much for the schema...            01/01/70 00:00      
               AVX varistors...            01/01/70 00:00      
                  capacitor            01/01/70 00:00      
                     capacitors...            01/01/70 00:00      
                        GNDs            01/01/70 00:00      
                           1992            01/01/70 00:00      
                              Thanks...            01/01/70 00:00      
                                 Links...            01/01/70 00:00      

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