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Create RS232 CAble

By Gel ·
Is there anybody know how to create a RS232 cable. Please give details.

Thanks

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Create RS232 CAble

by VinnyD In reply to Create RS232 CAble

There a number of different configurations of rs-232 cables.

You did not say what you need it for.

But here is a general one.

25 Pin 25 Pin
1 Shield Ground 1
2 Transmit 3 3 Recv 2
4 RTS 5
5 CTS 4
7 Ground 7
(the above wire from one connector to the other)
This get wired on one connnect only!
6, 8, &20 6, 8, & 20
One one connector wire pins 6, 8, and 20 together.

This creates a null modem cable for connnecting 2 serial devices together.

You can use this type of configuration to connect 2 computers together.

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Create RS232 CAble

by Gel In reply to Create RS232 CAble

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Create RS232 CAble

by SixFourtyKilo In reply to Create RS232 CAble

We create RS232 all the time and we use the following 25-pin standard which may or may not be beneficial to you:

1______________
\xxxxxxxxoooooo\ (1-
\xoxooxoooooooo\ (15,17,21)
15---------------

The important thing is that the cable is straight-through, where the colors match up on both sides. Larger cables sometimes have grey twisted with colors. If this is the case, you will need to un-sheath a larger portion of cable to see where the colors and greys twist together.

Hope this helps!
640k

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Create RS232 CAble

by SixFourtyKilo In reply to Create RS232 CAble

OOOPS! Sorry, I hadn't realized that the dumb little pic would be destroyed. We use pins 1-8 and 15,17,21.

640k

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Create RS232 CAble

by Gel In reply to Create RS232 CAble

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Create RS232 CAble

by cavedweller In reply to Create RS232 CAble

If you have a black-box catalog handy, they have a nice reference section. Unfortunately, RS-232 isn't a standard with a single solution.

As a minimum, you need the transmit, receive and signal return leads (25pin: 2, 3, 7) (9pin: 2, 3, 5). This will allow you to communicate with either no handshaking or software (XON/XOF) handshaking.

Sometimes you will need a "null modem" or "reversed" connection. Here's how to tell. Use a voltmeter on pins 2 or 3 of each connector with no cable connected. Use a paper clip if your probe doesn't fit into the socket. If you get at least -5 volts between 2 or 3 and the signel return then the device is talking on that line. If you get any other reading the device is listening. You need to connect the talking pin on one device to the listening pin on the other. This test will determine if you need to connect 2-3 & 3-2 or 2-2 & 3-3. You must always connect the signal returns (5 or 7).

If you don't have a meter just try one way and if it doesn't work, reverse pins 2 and 3 on one end of the cable.

By the way, the functions of pins 2 and 3 are reversed between the 9-pin and 25-pin implementation. Just use the voltmeter test and don't worry about whether you cable should be called straight or reversed.

If you need hardware handshaking you need to connect a lot more wires and the exact connections depend on your 2 devices. External modems require hardware handshaking and you are usually better off buying the cable if possible.

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Create RS232 CAble

by Gel In reply to Create RS232 CAble

Thanks it worked!

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Create RS232 CAble

by Gel In reply to Create RS232 CAble

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