> For the complete documentation index, see [llms.txt](https://docs.coupler.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coupler.io/sources/category/other/castor-edc/faq.md).

# FAQ

<details>

<summary>Can I export data from multiple Castor EDC studies in one data flow?</summary>

Castor EDC's API returns data across all studies your account has access to for most entities. For example, the Studies entity will list every study you can access. For entities like study visits or study forms, records from all accessible studies are included. If you need to separate them by study, you can filter the output in your destination or use Coupler.io's transformation options.

</details>

<details>

<summary>Where do I find my Castor EDC Client ID and Client Secret?</summary>

Log in to your Castor EDC account and go to **Account Settings**. Look for the API or developer section where credentials are managed. If you don't see this option, API access may need to be enabled by your organization admin or may require a plan upgrade.

</details>

<details>

<summary>What does the URL region setting do, and which one should I pick?</summary>

Castor EDC operates separate instances for the UK, Netherlands (NL), and US. Your data lives in only one of these regions — the one you registered with. Pick the region that matches your Castor EDC account URL (e.g., if you log in at uk.castoredc.com, choose "uk"). Using the wrong region will cause authentication to fail.

</details>

<details>

<summary>What is the difference between Audit trials and Study statistics?</summary>

Audit trials (audit trail) are a row-by-row log of every action taken in the system — who changed what, when, and what the value was before and after. Study statistics are aggregated metrics like enrollment counts, completion rates, and open query counts. Use audit trails for compliance and traceability; use study statistics for high-level progress reporting.

</details>

<details>

<summary>Why are study field dependencies and validations empty?</summary>

These entities only contain records if your study design includes conditional field logic (dependencies) or validation rules (validations). If you haven't configured these in Castor EDC, the entities will return no rows. This is expected behavior, not a connection error.

</details>

<details>

<summary>Can I use Castor EDC data with AI tools like ChatGPT or Claude?</summary>

Yes. Coupler.io supports AI destinations including ChatGPT, Claude, Gemini, Cursor, Perplexity, and OpenClaw. You can send your Castor EDC study data — like statistics, visit summaries, or form structures — directly to these tools to generate analysis, summaries, or documentation.

</details>

<details>

<summary>How do I combine data from study visits and study sites?</summary>

Add both **Study visits** and **Study sites** as sources in the same Coupler.io data flow, then use the **Join** transformation to link them on the site ID field. This gives you a single table showing visit activity broken down by location — useful for multi-site trial management.

</details>

<details>

<summary>How current is the data after a sync?</summary>

The data reflects the state of your Castor EDC instance at the moment the data flow runs. There is no real-time streaming — each run captures a snapshot. For time-sensitive use cases like audit trail monitoring, schedule more frequent refreshes.

</details>

{% hint style="info" %}
For a full list of available entities and what data each one contains, see the [Data Overview](/sources/category/other/castor-edc/data-overview.md) article. For help with connection errors or missing records, check [Common Issues](/sources/category/other/castor-edc/common-issues.md).
{% endhint %}


---

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