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usb to serial converter

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Hello, I need to communicate my PC to a device with a serial port (rs232). Nevertheless, I haven't got an available serial port on my CPU, so I was thinking about using a USB to Serial Converter. However, I've never used one before. My question is whether these converters are ALWAYS bidirectional or some work only one way. if so, are there ANY bidirectional converters or if unidirectional, can they communicate from the PC to the device? Here's the thing, when I went to the store to get one, I was told it communicates only from the device to the PC and I need it the other way around. Since this is kind of urgent, I intend to use a converter that is NOT from National Instruments. However, the control software for the device is a VI.

 

Also, if I can use the converter to communicate data from the PC to the device, does LabView detect the port as a normal serial port or do I have to make my VI for controlling the usb port?

 

Thanks,

Ali

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A normal USB to serial connection is like a plug in serial board. it simply adds a new serail device to your pc and you can use it like a comport as soon as the driver is installed.
greetings from the Netherlands
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I have been using a Belkin F5U109 for several years. It was originally billed as a "PDA adapter", but it is a bi-directional USB to DB9 adapter. It works with everything that I have tried over the years, including the inordinately ornery Allen-Bradley series software. Heck, it even works with, wait for it, VISTA.

Hope this is of some help,,

 

Dave

 

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I have never heard of one that is 'unidirectional'. What kind of store did you go to where they are selling such a thing?

 

I have used several types and though I don't remember brand names, I've had very good luck with those that use the ftdi chip set. There have been a couple threads about makes and models that work well with LabVIEW and those that need a little extra work. You can do a search of this and the LabVIEW board. Also, not all of the converters support hardware handshaking so if this is something you need, you will probably have to spend a little bit more and read the specs of the device.

 

The majority of converters will have a driver that automatically makes it appear in windows as just another serial port and it will also appear that way to MAX and hence to LabVIEW.
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We've had once a single-directional USB-serial connector.

It gave us rare problems, we could write to the device, but couldn't read. Until I asked my colleague if he had installed the drivers...  :smileysurprised:

 

Ton

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Hi Ali84;

 

As far as I have heard converters are bidirectional so that's not a problem, about what you need for the converter to work with LabVIEW you need mainly two Drivers: your converters driver and a VCP (Virtual Communication Port) which generates a virtual port linked to your converter. The following is a link to a Forum discussing the topic.

 

http://forums.ni.com/ni/board/message?board.id=170&message.id=221413&requireLogin=False

 

Hope the information is useful.

 

Good Luck

 

Francisco Arellano

Francisco Arellano

National Instruments Mexico
Field Systems Engineer - Energy Segment
www.ni.com/soporte
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Accepted by topic author Ali84

Thanks everyone for your replies. I've also been thinking of buying a pci card with two serial ports for the PC since I think they're a bit more reliable. ANyway, I've tested the converter and so far it has worked fine. THanks again.

Ali

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