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Re: serial port transmission
The confusion over the "inversion" of the signal level by the MAX232 has to do with the volatge levels.
When the SIO line is Idle (or Marking) the logic level signal is positive, but the RS232 level is negative. And when the line is 'Spacing' the logic level signal is at ground and the RS232 level is positive. So in respect to the logic level, the RS232 level is 'inverted'.
When you are connected RS232 to RS232 you don't have to be concerned with the levels. However, to save costs, engineers sometimes replace the MAX232 with a clamping diode and resistor network to convert the RS232 votage to a TTL voltage. But when you do that, the resulting signal is inverted (voltage wise), and therefore you need to invert it.
So, if you are connecting RS232 to RS232, you don't need to worry about inverting the signal.
The confusion over the "inversion" of the signal level by the MAX232 has to do with the volatge levels.
When the SIO line is Idle (or Marking) the logic level signal is positive, but the RS232 level is negative. And when the line is 'Spacing' the logic level signal is at ground and the RS232 level is positive. So in respect to the logic level, the RS232 level is 'inverted'.
When you are connected RS232 to RS232 you don't have to be concerned with the levels. However, to save costs, engineers sometimes replace the MAX232 with a clamping diode and resistor network to convert the RS232 votage to a TTL voltage. But when you do that, the resulting signal is inverted (voltage wise), and therefore you need to invert it.
So, if you are connecting RS232 to RS232, you don't need to worry about inverting the signal.