update faq

Author: frankie-zeng

docs/en/faq/index.md

@@ -73,3 +73,13 @@ setInterval(() => {
 ```
 
 :::
+## Can I use a custom sub-function for preset `0x27 (SecurityAccess)` commands? (for example `0x35` / `0x36`)
+
+::: details Answer
+Yes. When configuring a preset `0x27` service, set the sub-function to custom and enter the target value, such as `0x35` (request seed) and `0x36` (send key).
+
+For security access, make sure the request-seed and send-key sub-functions are paired correctly (typically odd/even pairs) and match your ECU implementation.
+
+Reference: [Issue #335 comment](https://github.com/ecubus/EcuBus-Pro/issues/335#issuecomment-4258104744)
+::::
+

docs/zh/faq/index.md

@@ -73,3 +73,12 @@ setInterval(() => {
 ```
 
 :::
+## 预设指令里的 `0x27 (SecurityAccess)` 子功能可以自定义吗？（例如 `0x35` / `0x36`）
+
+:::details 答案
+可以。在预设指令中配置 `0x27` 服务时，将子功能设置为自定义并输入目标值即可，例如 `0x35`（请求种子）和 `0x36`（发送密钥）。
+
+对于安全访问场景，请确保请求种子和发送密钥的子功能配对正确（通常为奇偶配对），并与ECU实现保持一致。
+:::
+
+参考链接： [Issue #335 comment](https://github.com/ecubus/EcuBus-Pro/issues/335#issuecomment-4258104744)