RS-232 Serial Port Sniffer

[MoReese]

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@Ravens Fan wrote:

A device such at this http://www.bb-elec.com/product_family.asp?familyid=33&webSyncID=3e948270-0e0d-6b02-d066-2e1530b3cac5... could come in handy for tapping into and monitoring a serial line.

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Thanks.  I am aware of the cable sniffer; however, it would require the use of two ports, in which case, I can just use a null cable to loop the signal back on the PC.  But this is a device I was not aware of before this discussion and would come in handy for troubleshooting purchases.

[MoReese]

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@MoReese wrote:

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One site made mention of this and noted that the computer could do this automatically but did not say what that meant or how to fix it.

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Here is the site that notes the problem but doesn't really say it is a problem.

http://divesoftware.org/libdc/contribute.html

[MaxCrunch]

One possible approach could be to use a com port redirector (there's lots of free ones) to redirect the serial port to an ethernet port, then connect to that port from LabVIEW.

I've used this before, but not to connect from the same machine. It should be possible though.

Good luck!

[MoReese]

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@MaxCrunch wrote:

One possible approach could be to use a com port redirector (there's lots of free ones) to redirect the serial port to an ethernet port, then connect to that port from LabVIEW.

I've used this before, but not to connect from the same machine. It should be possible though.

Good luck!

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This might be a possible solution.  Thanks for the input.

[Chazzzmd]

MoReese,

The most direct way I found to accomplish this is to just simply hookup an RS232 splitter cable from the PC's serial port. Leave one side of split cable alone, then on the other just clip the rest that you do not need, leaving only the RX cables (I think there's a total of 2 or 3 you leave alone). The one side of the split you left alone is what is used for your application already, the other one you clipped? Well, just hook it up to a RS232 to USB cable (I prefer Prolific because the drivers are usually already, but for WIN 98 I doubt). Now you can sniff all traffic on your applications line through the newly generated COM port which was generated by the RS232 to USB cable. From there (in labview) all you have to do is read the bytes in a loop off the new COM port. No interference issues should arise. 

-Chazzzmd

[MoReese]

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@Chazzzmd wrote:

MoReese,

The most direct way I found to accomplish this is to just simply hookup an RS232 splitter cable from the PC's serial port.

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Are you talking about a Y-splitter? Or 1:3 or more?

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Leave one side of split cable alone, then on the other just clip the rest that you do not need, leaving only the RX cables (I think there's a total of 2 or 3 you leave alone).

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What do you mean by this?  By clip, you mean cut, right?  What do you mean by RX cable?

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@Chazzzmd wrote:

MoReese,

The one side of the split you left alone is what is used for your application already, the other one you clipped? Well, just hook it up to a RS232 to USB cable (I prefer Prolific because the drivers are usually already, but for WIN 98 I doubt). Now you can sniff all traffic on your applications line through the newly generated COM port which was generated by the RS232 to USB cable. From there (in labview) all you have to do is read the bytes in a loop off the new COM port. No interference issues should arise. 

-Chazzzmd

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Perhaps a diagram would be better to indicate what you're talking about.  Sorry, it's not too clear to me.  How do I hookup an RS-232-USB converter to a serial port/cable?  Unless you're indicating that the converter should be hooked up to the cable and then plugged into a USB port to act as a loop-back.  I think this is what you are saying.  This is basically doing the same thing as a cable sniffer, which is what it is.  This would be OK for lack of RS-232 ports, but if I have the 232 ports available, you can't beat the simplicity of using a null cable.  This is a good solution for my laptop, so thanks for the input.  I appreciate it.