# RFU on Win7

**URL:** <https://forums.digi.com/t/rfu-on-win7/10686>\
**Category:** Rabbit\
**Created:** [February 29, 2012, 11:39pm UTC](https://forums.digi.com/t/rfu-on-win7/10686 "2012-02-29T23:39:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![SeeCwriter](https://avatars.discourse-cdn.com/v4/letter/s/ea666f/32.png) [@SeeCwriter](https://forums.digi.com/u/SeeCwriter)\
**Post date:** [February 29, 2012, 11:39pm UTC](https://forums.digi.com/t/rfu-on-win7/10686/1 "2012-02-29T23:39:54Z")

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I am changing PCs from a WinXP to Win7 64-bit. I installed DC 9.25  
and the RFU that comes with it works fine. I installed DC 10.66 but  
the RFU that comes with it fails to download. I have it configured the  
same as it was on my WinXP PC.

Programming is done over an RS-232 port, not USB and there is no  
USB-to-Serial converter invovled. I can communicate with the unit  
over the serial port, I just can’t program.

Steve

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**Author:** ![cpigilam](https://avatars.discourse-cdn.com/v4/letter/c/fbc32d/32.png) [@cpigilam](https://forums.digi.com/u/cpigilam)\
**Post date:** [May 18, 2012, 2:36pm UTC](https://forums.digi.com/t/rfu-on-win7/10686/2 "2012-05-18T14:36:01Z")

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Hello, which Rabbit module are you using?

You need to select Dynamic C version, based on your module. Dynamic C 9.xx works for Rabbit 2000,3000 processors and Dynamic C 10.xx works for Rabbit 4000,5000 and 6000 processors.