# Debugging - node-red-contrib-modbus - serial RTU

**URL:** <https://discourse.nodered.org/t/debugging-node-red-contrib-modbus-serial-rtu/40780>\
**Category:** General\
**Created:** [10 February 2021 20:42 UTC](https://discourse.nodered.org/t/debugging-node-red-contrib-modbus-serial-rtu/40780 "2021-02-10T20:42:26Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![Ion3](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ion3/32/36892_2.png) [@Ion3](https://discourse.nodered.org/u/Ion3)\
**Post date:** [10 February 2021 22:14 UTC](https://discourse.nodered.org/t/debugging-node-red-contrib-modbus-serial-rtu/40780/6 "2021-02-10T22:14:22Z")

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> [@craigcurtin](#):
>
> Do a search on the forum - about 2 months ago this same issue came up and was i believe resolved.

Did you have [this](https://discourse.nodered.org/t/cant-get-serialport-to-work/6719/11) in mind? Just to give it a try:

```auto
sudo chmod a+rw /dev/ttyUSB0

```

Without luck. 🤔

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_[View the full topic](https://discourse.nodered.org/t/debugging-node-red-contrib-modbus-serial-rtu/40780)._