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JokeRe: Thought of the Day Pin
Johnny J.14-Feb-19 21:22
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MacSpudster15-Feb-19 6:31
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Bassam Abdul-Baki21-Feb-19 5:32
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GeneralThought of the Weak Pin
MacSpudster14-Feb-19 4:21
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W Balboos, GHB14-Feb-19 6:03
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GeneralSerial cables... serial communications Pin
charlieg14-Feb-19 3:10
Membercharlieg14-Feb-19 3:10 
It's not a programming question Shucks | :-\

Maybe someone's serial cable fu is better than mine. I'm looking for some practical insight on serial communications at the PC level. Older machines, larger boxes may still have built in com ports exposed at the back, but most of us are living in the land of usb to serial. For the sake of discussion, the ports in use are confirmed to have the same settings - 9600 baud, 8 bit, 1 stop bit, no handshake or anything else....

Living in the embedded world, we'll solder up a home made serial cable in a few minutes - DB9 to DB9 - connector pins 2-3, pin 5 for the ground (swapping pin 2 and 3 gives you a null modem cable). On the embedded hardware, this is typically all we need to do... but I'm finding PC level usage of this hand crafted cable problematic. If I take a typical null modem cable: 10 ft DB9 RS232 Serial Null Modem Cable | Null Modem Serial Cables | StarTech.com[^] everything works fine.

If I take my stripped down special, no communications. I've verified that both cables are wired the same - with the exception that the commercial product connects the other 6 pins according to standards. I've been told these other connections are not necessary, but said engineers are talking to embedded hardware not another PC.

Wondering if an CP folks have some practical scars and insights in this area that would shed some light on this behavior. I'm going to tell the customer to go buy a serial cable, but now I'm curious.

thanks
Charlie Gilley
<italic>Stuck in a dysfunctional matrix from which I must escape...

"Where liberty dwells, there is my country." B. Franklin, 1783
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759

GeneralRe: Serial cables... serial communications Pin
RickZeeland14-Feb-19 3:16
mveRickZeeland14-Feb-19 3:16 
GeneralRe: Serial cables... serial communications Pin
charlieg14-Feb-19 4:09
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GeneralRe: Serial cables... serial communications Pin
Munchies_Matt14-Feb-19 3:53
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GeneralRe: Serial cables... serial communications Pin
charlieg14-Feb-19 4:07
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GeneralRe: Serial cables... serial communications Pin
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GeneralRe: Serial cables... serial communications Pin
charlieg14-Feb-19 16:37
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GeneralRe: Serial cables... serial communications Pin
Munchies_Matt14-Feb-19 21:49
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GeneralRe: Serial cables... serial communications Pin
jeron114-Feb-19 4:21
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GeneralRe: Serial cables... serial communications Pin
lopatir14-Feb-19 4:06
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GeneralRe: Serial cables... serial communications Pin
Klaus-Werner Konrad14-Feb-19 4:39
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GeneralRe: Serial cables... serial communications Pin
PIEBALDconsult14-Feb-19 5:14
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GeneralRe: Serial cables... serial communications Pin
Mark_Wallace14-Feb-19 5:17
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GeneralRe: Serial cables... serial communications Pin
Munchies_Matt14-Feb-19 5:58
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GeneralRe: Serial cables... serial communications Pin
0x01AA14-Feb-19 5:37
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GeneralRe: Serial cables... serial communications Pin
charlieg14-Feb-19 16:41
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GeneralRe: Serial cables... serial communications Pin
charlieg15-Feb-19 1:57
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GeneralRe: Serial cables... serial communications Pin
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