On 12/13/17 23:03, Russell Senior wrote: > The precise levels are not supposed to make a difference. Below a > negative threshold and above a positive threshold should be enough. > From memory, original RS232 was +/- 12V, but any remotely modern PC > would use +/- 5V-ish.
And the reality is that in most cases a simple unipolar TTL signal will work. RS232 receivers usually have the logic threshold near +1.4V, plus or minus some hysteresis. For example, the TI MAX232 has a typical positive-going threshold of +1.7V, and a negative-going threshold of +1.2V. Another older example is the OnSemi MC1489A quad RS232 receiver. The typical thresholds for this device are +1.95V and +0.8V. galen -- Galen Seitz gal...@seitzassoc.com _______________________________________________ PLUG mailing list PLUG@pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug
