# Cpu x20cp1684 **URL:** \ **Category:** B&R Software & Runtime\ **Tags:** plc\ **Created:** [June 29, 2026, 4:43pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752 "2026-06-29T16:43:30Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![electrofasa21](https://avatars.discourse-cdn.com/v4/letter/e/FF8800/32.png) [@electrofasa21](https://community.br-automation.com/u/electrofasa21)\ **Post date:** [June 29, 2026, 4:43pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/1 "2026-06-29T16:43:30Z")
Hello, very good to everyone, delighted to transmit and receive knowledge. My CPU XP20CP1684 with automation studio 4.12 and RUMTIME 3.90 does not work the R/E led remains solid red the RYDE led is in Off and the S/E led is also in Off what can we do to make our CPU come out again in this way? ---
**Author:** ![marcusbnr](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/marcusbnr/32/256_2.png) [@marcusbnr](https://community.br-automation.com/u/marcusbnr)\ **Post date:** [June 29, 2026, 5:07pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/2 "2026-06-29T17:07:52Z")
Hi Julián, Normally a solid red R/E light means that the PLC is in Boot or Service mode. However, if the RDY/F light is not on at all, I’m thinking it’s not even getting to that point. ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/b/b92bc47036f8a79730478f60dae18041d3416a1e.png) A couple of questions for you: 1. Was this PLC being used on a machine when it stopped working, or did you recently change hardware/update the software? 2. Are you able to see and/or connect to it from Automation Studio? ---
**Author:** ![electrofasa21](https://avatars.discourse-cdn.com/v4/letter/e/FF8800/32.png) [@electrofasa21](https://community.br-automation.com/u/electrofasa21)\ **Post date:** [June 29, 2026, 6:32pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/3 "2026-06-29T18:32:02Z")
Question 1. The PLC happened while working with the machine, it was working, it has NOT happened after a software update. The hardware has been working properly for 2/3 years without problems, it has not been replaced Question 2. The connection via ethernet is dead, we know the IP but the controller is not found. ---
**Author:** ![marcusbnr](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/marcusbnr/32/256_2.png) [@marcusbnr](https://community.br-automation.com/u/marcusbnr)\ **Post date:** [June 29, 2026, 7:05pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/4 "2026-06-29T19:05:11Z")
Unfortunately this sounds a lot like a hardware failure to me. It’s possible the issue is just with the CompactFlash card. If you have a spare card that you know works, you could try installing the Automation Studio project on it, or even just a blank project with the correct hardware for testing. If you can’t get the PLC to boot with a known-working card though, the issue is probably with the PLC itself. I’d recommend reaching out to your local B&R support contact to figure out what your options are. ---
**Author:** ![electrofasa21](https://avatars.discourse-cdn.com/v4/letter/e/FF8800/32.png) [@electrofasa21](https://community.br-automation.com/u/electrofasa21)\ **Post date:** [June 29, 2026, 8:29pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/5 "2026-06-29T20:29:57Z")
We will try to try with a card like t flash new. Thank you. ---
**Author:** ![marcusbnr](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/marcusbnr/32/256_2.png) [@marcusbnr](https://community.br-automation.com/u/marcusbnr)\ **Post date:** [June 30, 2026, 12:16pm UTC](https://community.br-automation.com/t/cpu-x20cp1684/11752/6 "2026-06-30T12:16:18Z")
You’re welcome, let us know if you need more help!