> On Feb 2, 2018, at 7:26 PM, Paul Berger via cctalk <cctalk@classiccmp.org>
> wrote:
>
>
>
> On 2018-02-02 7:13 PM, Fred Cisin via cctalk wrote:
>>> they might have different ground systems. If so, grounding both ends might
>>> produce a LARGE current through the cable, possibly enough to be hazardous.
>>
>> OB_Ignorant_Question: Is that the reason why RS232 DB25 has both pin 1 and
>> pin 7?
> Pin 1 is supposed to be protective (shield) ground and pin 7 is signal
> ground.
>
> Paul.
Similar to safety ground (green) and neutral (white, in the USA) on power
wiring.
paul
