null modem cable compared with serial cable ?

  • Thread starter Thread starter jameshanley39
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jameshanley39

how can you tell the difference between a null modem cable and a
serial cable?

i've heard that a null modem cable is for connecting 2 computers
together. So I guess a serial cable is just for connecting a computer
to a device. ?

Is it like a straight through vs a crossover ?
 
how can you tell the difference between a null modem cable and a
serial cable?

i've heard that a null modem cable is for connecting 2 computers
together. So I guess a serial cable is just for connecting a computer
to a device. ?

Is it like a straight through vs a crossover ?
Click to expand...

Yes, same idea. Somewhere around here, I have a four-ended null
modem cable: DB9 and DB25 pair at each end. It's easy to recognize
that one as a null modem cable. Not so easy with one having only
two connectors. You can check continuity for one of the crossed
connections (transmit on one end to receive on the other). It
is wise to mark a null modem cable with a tape label or write on
the jacket directly.
 
how can you tell the difference between a null modem cable and a
serial cable?

i've heard that a null modem cable is for connecting 2 computers
together. So I guess a serial cable is just for connecting a computer
to a device. ?

Is it like a straight through vs a crossover ?
Click to expand...

Yes.
A serial cable creates a straight connection.
Typically between a DTE (like a PC) and a DCD (modem).

A cross-cable allows you to make a connection between two similar
devices (like 2 PCs).
It does that by connecting Sender to Receiver pins and vise
versa.
Details: www.hardwarebook.info
There, you can also see that a straight cable is always the same
cable while a crossover may come in many forms and shapes.
Some crossed cables may not work in a given situation!
 
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