# Digital channels stop working

**URL:** <https://discuss.saleae.com/t/digital-channels-stop-working/2517>\
**Category:** Logic 2 Software\
**Created:** [October 31, 2023, 7:33pm UTC](https://discuss.saleae.com/t/digital-channels-stop-working/2517 "2023-10-31T19:33:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![shane](https://avatars.discourse-cdn.com/v4/letter/s/dbc845/32.png) [@shane](https://discuss.saleae.com/u/shane)\
**Post date:** [October 31, 2023, 7:33pm UTC](https://discuss.saleae.com/t/digital-channels-stop-working/2517/1 "2023-10-31T19:33:24Z")

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Digital channels stopped working this morning. Analog channels still work perfectly. Tested on all 8 channels of my Logic Pro 8. Software is Logic 2 v2.4.10

 ![Screenshot from 2023-10-31 12-30-11](https://canada1.discourse-cdn.com/flex030/uploads/saleae/original/2X/c/ce25d17e096fc28080733bd5451f711c4600f1dd.png)

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**Author:** ![markgarrison](https://yyz2.discourse-cdn.com/flex030/user_avatar/discuss.saleae.com/markgarrison/32/23_2.png) [@markgarrison](https://discuss.saleae.com/u/markgarrison)\
**Post date:** [November 2, 2023, 4:22pm UTC](https://discuss.saleae.com/t/digital-channels-stop-working/2517/2 "2023-11-02T16:22:18Z")

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Sorry for the trouble @shane !

From the analog capture, it looks like the signal is not swinging down to ground, it only goes down to about 0.75 volts.

With the digital threshold set to 1.2V logic, the actual threshold used by the device is about 0.6 volts.

Two things to look into:

1. Change your logic level (next to the digital sample rate) to 3.3V.
2. Check for in improper ground connection. If your digital signal should be swinging to ground, but Logic is showing it above ground, there could be a (potentially damaging) electrical connection problem between Logic 2, your device under test, and potentially whatever is powering your device under test. Double check that the Logic Pro 8’s ground pin(s) are connected to ground on your device under test, and not to any other voltage. Keep in mind that Logic Pro 16’s ground pins are connected to the USB port ground, which is connected to your PC ground, and shared between everything else connected to your PC. It is sometimes possible to get into trouble here in ways that are not obvious. We have more detail here: [https://support.saleae.com/user-guide/safety-and-warranty#ground-current-safety](https://support.saleae.com/user-guide/safety-and-warranty#ground-current-safety)  
Note, USB isolators are not required in most applications.