# CF Card stops functioning once variable is changed

**URL:** <https://community.br-automation.com/t/cf-card-stops-functioning-once-variable-is-changed/2827>\
**Category:** B&R Software & Runtime\
**Tags:** automation-studio, automation-runtime\
**Created:** [April 8, 2024, 6:12pm UTC](https://community.br-automation.com/t/cf-card-stops-functioning-once-variable-is-changed/2827 "2024-04-08T18:12:33Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**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:** [April 8, 2024, 6:30pm UTC](https://community.br-automation.com/t/cf-card-stops-functioning-once-variable-is-changed/2827/3 "2024-04-08T18:30:28Z")

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Hi Zachary,

Welcome to the community!

As you said, the issue is probably in the program code rather than an issue with the card itself. Service mode means that a critical error occurred during runtime that the application couldn’t recover from. One possibility is that changing the value of this variable is causing a memory access violation or a divide by zero error for example.

In order to figure out what specifically is going wrong, you’ll need to take a look at the system log. This can be done from Automation Studio or by getting a log file off of the panel. There was a previous post that shows you how to do this [here](https://community.br-automation.com/t/service-mode-what-is-it-and-how-to-collect-diagnostics/1613).

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