# Features & Limitations

> For the complete documentation index, see [llms.txt](https://help.1nce.com/llms.txt).

# Features

* Sending messages to IoT devices using UDP, CoAP and LwM2M.
* Message for single device and [bulk devices](/docs/v2/1nce-os/1nce-os-device-controller/device-controller-api/#bulk-request) are supported.
* Schedule message to be send when we receive a message from the device or on LwM2M registration and update events (requestMode `SEND_WHEN_ACTIVE`)
* Cross-protocol trigger: sending a message from the device with any protocol to the 1NCE OS endpoint will trigger sending scheduled messages for all protocols to the device
* Possibility to cancel a scheduled request
* Possibility to cancel all scheduled requests for a device
* See the response from the device for CoAP and LwM2M
* Possibility to configure [retries](/docs/v2/1nce-os/1nce-os-device-controller/device-controller-api/#retry-mechanism) for scheduled CoAP or LwM2M messages.
* Track the status of action requests. Available values:
  * `SCHEDULED`: the request was created with requestMode `SEND_WHEN_ACTIVE`. The request hasn't been sent to device and is still pending for a trigger to occur.
  * `IN_PROGRESS`: the request was created with requestMode `SEND_NOW`, or was scheduled and a trigger occurred
  * `SUCCEEDED`: device responded with 2.xx response code via CoAP or LwM2M. Or message was sent via UDP (there's no validation a message via UDP was received).
  * `FAILED`: device responded with 4.xx or 5.xx response code via CoAP or LwM2M. Or an unexpected error occurred. Check the `resultData` of the request for more details. Only for CoAP, if the actual response data fails to be saved (e.g. malformed payload), then the Action request finishes with a `FAILED` state.
  * `CANCELLED`: a scheduled request was cancelled via the DELETE endpoints of our API

<div style={{textAlign: 'center'}}>
![Action request lifecycle](/img/1nce-os/1nce-os-device-controller/device-controller-features-limitations/device-controller.png)
</div>

***

# Limitations

:::warning
For CoAP Actions the device should send ACK to Device Controller IP from which the message was received **instead of sending ACK to[CoAP Server](/docs/v2/1nce-os/1nce-os-device-integrator/device-integrator-coap/)**
:::

* A maximum of 10 Messages can be scheduled per device
* Maximum 100 devices are allowed to be selected for each request
* Scheduled messages (requestMode `SEND_WHEN_ACTIVE`) are expired and sent to `FAILED` status if not triggered during 24 hours
* Requests will be deleted 7 days after the creation date, independent of the status of the request.
* A maximum UDP payload size of 508 bytes
* A maximum CoAP payload size of 1024 bytes
* CoAP DTLS is currently not supported
* The maximum number of send attempts for SEND_WHEN_ACTIVE requests is 5.
* For CoAP Actions only, the response body (if available) will be visible as either a plain string or a Base64 encoded value, depending on the Content-Format of the response. If no Content-Format is provided, then Base64 is the default one.
* According to [RFC7252 section 4.8](https://www.rfc-editor.org/rfc/rfc7252.html#section-4.8), the end timeout for a CoAP message with default retransmission (maximum 4 retransmits) and exponential backoff can range from approximately 62 to 93 seconds.
* 1NCE OS is currently only available through the Europe (Frankfurt), US East (N. Virginia), and Asia-Pacific (Tokyo) breakout regions. For more details, see [Internet Breakout](/docs/v2/network-services/network-services-internet-breakout/).