Hi all,
I have wire up two circuit that are same to communication between 2 computer:
+ Rs232 to rs485
+ Rs485 to rs232
Both circuit of 555 timer to control receiver and transmiter.And two circuit are identical and half dulex.I have program to trnsmit data to comm port but there is a strange that happen.It can transmit data from one breadboard_1 to breadboard_2 but I can not transmit it from the breadboard_2 to breadboard_1 despite they are identical.I have check all connection of them and they are good.I also check idle state of them and they are same.Would you show me what really happen in this? And I have a confusion about the 232 standard.I know that:
+ 1 logic <=> -12 to -3 V
+ 0 logic <=> 3V to 12V
but when I transmit data and I used Voltmeter to measure the voltage of TX and I supprise that the voltage is always negative about -11V.I don't know this happen.I think the data have many 0 and 1 logics and the TX have to have all value from -12v to +12v
I have wire up two circuit that are same to communication between 2 computer:
+ Rs232 to rs485
+ Rs485 to rs232
Both circuit of 555 timer to control receiver and transmiter.And two circuit are identical and half dulex.I have program to trnsmit data to comm port but there is a strange that happen.It can transmit data from one breadboard_1 to breadboard_2 but I can not transmit it from the breadboard_2 to breadboard_1 despite they are identical.I have check all connection of them and they are good.I also check idle state of them and they are same.Would you show me what really happen in this? And I have a confusion about the 232 standard.I know that:
+ 1 logic <=> -12 to -3 V
+ 0 logic <=> 3V to 12V
but when I transmit data and I used Voltmeter to measure the voltage of TX and I supprise that the voltage is always negative about -11V.I don't know this happen.I think the data have many 0 and 1 logics and the TX have to have all value from -12v to +12v