# Enabling RS 485 on Hummingboard2, Debian 4.9.150

**URL:** <https://community.solid-run.com/t/enabling-rs-485-on-hummingboard2-debian-4-9-150/664>\
**Category:** I.MX6\
**Created:** [June 16, 2023, 8:07am UTC](https://community.solid-run.com/t/enabling-rs-485-on-hummingboard2-debian-4-9-150/664 "2023-06-16T08:07:00Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![john](https://avatars.discourse-cdn.com/v4/letter/j/a3d4f5/32.png) [@john](https://community.solid-run.com/u/john)\
**Post date:** [June 16, 2023, 8:07am UTC](https://community.solid-run.com/t/enabling-rs-485-on-hummingboard2-debian-4-9-150/664/1 "2023-06-16T08:07:00Z")

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Hello,

I am trying to enable the RS485 port, but ttymxc1 doesn’t show up in /dev (ttymxc0 and ttymxc2 are there).

I tried to follow the instructions here:

[https://solidrun.atlassian.net/wiki/spaces/developer/pages/270631021/HummingBoard+CBi+Quick+Start+Guide](https://solidrun.atlassian.net/wiki/spaces/developer/pages/270631021/HummingBoard+CBi+Quick+Start+Guide)

```auto
Hit any key to stop autoboot: 0
=> setenv is_cbi 1
=> saveenv
=> reset

```

However, the setting `is_cbi = yes` causes the board to fail to boot, because the dtb file is not included in the device tree files:

```auto
Failed to load '/boot/dtbs/4.9.150-imx6-sr/imx6dl-hummingboard2-cbi-emmc-som-v15.dtb'

```

What is the best way to get RS 485 working in the latest software?

Thanks,  
John

---

<div class="post-metadata">

**Author:** ![jnettlet](https://dub1.discourse-cdn.com/flex005/user_avatar/community.solid-run.com/jnettlet/32/62_2.png) [@jnettlet](https://community.solid-run.com/u/jnettlet)\
**Post date:** [June 18, 2023, 5:23am UTC](https://community.solid-run.com/t/enabling-rs-485-on-hummingboard2-debian-4-9-150/664/2 "2023-06-18T05:23:11Z")

</div>

Are you using Debian’s kernel, or our patched kernel?

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<div class="post-metadata">

**Author:** ![john](https://avatars.discourse-cdn.com/v4/letter/j/a3d4f5/32.png) [@john](https://community.solid-run.com/u/john)\
**Post date:** [June 19, 2023, 7:24am UTC](https://community.solid-run.com/t/enabling-rs-485-on-hummingboard2-debian-4-9-150/664/3 "2023-06-19T07:24:24Z")

</div>

Hi,

I am using the latest Debian image from SolidRun: sr-imx6-debian-buster-20220731-cli.img.xz

Thanks,  
John