decyL Posted December 6, 2005 Report Share Posted December 6, 2005 Hello. Has anyone ever tried to add usb device in the way described on NI website: http://zone.ni.com/devzone/conceptd.nsf/we...16?opendocument What's more - please give me piece of advice - is it worth to buy usb converters (to RS-485, to RS-422) instead of using PCI cards? I've heared that it is slower, and what about LV drivers? If using USB should I write communication protocol to the devices to communicate in LV? Help me. Greets Quote Link to comment
Irene_he Posted December 6, 2005 Report Share Posted December 6, 2005 Most time you don't really need to write USB driver for the device you use unless that is your own created device. If using USB RS232 converter, it's transparent to your existing software that can talk to RS232, you don't need to change anything in your software, the only thing you need is install the USB RS232 converter driver, then it'll add a virtual com port to your computer like any other COM port. If you decide to use other USB devices, like USB DAQ, you also don't need to write your own driver because most of the USB DAQs will come with drivers and programming interface for your languages such as LabVIEW. Irene Quote Link to comment
didierj Posted December 7, 2005 Report Share Posted December 7, 2005 Speed of USB to serial converter shouldn't be an issue. USB1 works at few Mbaud and USB2 works at up to 400Mbaud. Serial ports works below 1Mbaud. Many RS-422/485 sytem work at 19,2kbaud or 115kbaud. I use USB to RS-422/485 converters quite often without problem. They are cheap (much cheaper than built-in PCI cards) and can be hooked to any computer (also some desktop and barebones without PCI-Slots). As Irene stated, the included drivers build additional com-ports that can be used by your app the same way as it would with COM1 or COM2, even when the USB-RS converter is connected to an USB-Hub. The only thing you have not to forget is to look up which port is installed by the driver. This varies from computer to computer. Quote Link to comment
decyL Posted December 7, 2005 Author Report Share Posted December 7, 2005 hmmm. I spoke to the guy from NI and he didn't recommend the converters especially when used in big projects involving a lot of equipment. What's more as far as I know there is a problem with the galvanic isolation in this converters - and this is also an important issue. Anyway it is worth knowing that such converters work and devices can be controlled from LV. Thanks for reply! Greetings Quote Link to comment
didierj Posted December 8, 2005 Report Share Posted December 8, 2005 hmmm. I spoke to the guy from NI and he didn't recommend the converters especially when used in big projects involving a lot of equipment. What's more as far as I know there is a problem with the galvanic isolation in this converters - and this is also an important issue. Anyway it is worth knowing that such converters work and devices can be controlled from LV. Thanks for reply! Greetings ...ok, I use the USB-Serial converter we sell ourselves (together with our pressure transmitters). They have galvanic isolation. Quote Link to comment
decyL Posted December 8, 2005 Author Report Share Posted December 8, 2005 could you give me any details where can I buy these converters with galvanic isolation? any website? regards Quote Link to comment
didierj Posted December 12, 2005 Report Share Posted December 12, 2005 We make them ourselves. Go to Keller Druck -> English -> Products -> Miscellaneous -> Converters. Under "Addresses" you'll find the address for our sales reps (unfortunately no online shop). Didier Quote Link to comment
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