Do i really need termination resistor in very short distance of rs485
- Thread starter anhnha
- Start date
panic mode
- Joined Oct 10, 2011
- 2,761
and what is "very short"? provide actual distance.
and what is 555 doing in RS232 or 485 connection?
and what is 555 doing in RS232 or 485 connection?
Non-standard RS232 drivers e.g. LM555 working against ground potential sometimes function without a negative supply--it depends upon the threshold level in your computer(s)--however, the signal zero level may be so close to the threshold that it may be flaky and not work all the time--I have seen this--make sure that the data voltage signal actually swings negative per the RS232 specification.
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Thanks.
and built it in breabboard.But It is not work.
I even received data without power supply and GND of comm port.As for the GND of comm port is conneced and power is tied it is not work.I think my circuit is have no problem.
Yes.I have just my circuit.
I used a PC to send and received.I want to test it at home before used it in fact.
No.My circuit is quite simple but I don't know why it is not work.I used the schematic in this:http://www.bb-elec.com/bb-elec/literature/485ptbr-3903ds.pdf
and built it in breabboard.But It is not work.
I even received data without power supply and GND of comm port.As for the GND of comm port is conneced and power is tied it is not work.I think my circuit is have no problem.
