Cable type

[Jayee]

Hi,

I have a cable with a Male 9-pin connector at one end and a Female 9-pin connector at the other end.

How do I tell if it's a standard serial cable or a null modem cable. I've been told the two types look identical, so how do I tell them apart ?

There is some wording on the cable itself - AWM 2464 800 C 300V 26AWG VW-1 OT LL107286 C5A AWM 1/N - does this mean anything ?

I hope you can help.

Regards,
Jay

 

[phannah]

You can get a tester designed to display the pinouts, or check each pin, either by removing the cover of the connector, if it's not molded, and if the wire is color coded, otherwise, you can check each pin with an ohmmeter/multimeter.

 

[skip555]

or you could try it in a null modem app and a non null modem app.

simplest is a non null modem , if it works a serial cable , then its not null modem. if not it may be null modem (or may be defective)

 

[franklin97355]

Usually null modem cables have female connectors on both ends.

 

[robertjo24]

Use a multimeter to ohm out the pins.

A straight through cable is just that, pin 2 on one end will have continuity to pin 2 on the other end. This will be the same for pin 3, pin 4, etc. A null modem cable will have pins 2 & 3 swapped.
If you do not have access to a multi-meter to measure the pins, make a simple continuity tester with a small flashlight bulb, a single AA battery, and some hook-up leads.

 

[DigitalG]

Here is a good link on serial communication hope it helps

http://www.arcelect.com/rs232.htm