The actual limiting factor is the load presented to the driver by the cable - principally the capacitance. It is irrelevant whether you have a short length of high-capacitance cable, or a long length of low-capacitance cable - it's the total capacitive load that makes the difference. That's why the spec just states a load requirement:

"The effective shunt capacitance (CL) of the receiver side of an interchange circuit, including the capacitance of cable, measured at the interface point, shall not exceed 2500pF."

Thanks Andy. I must confess that I never read actual RS232 specifications, means source documents, only 'copies' and 'tutorials'. And these talked about 'maximum cable length'. Now I'm happy to hear, that NOT cable length is relevant but capacitive load. This is indeed the only that really makes sense!

Isn't it amazing how much garbage is published in the net and other 'serious' electronic publishings?

Andy, many thanks again for this valuable information!!

Kai