> For the complete documentation index, see [llms.txt](https://developer.magtek.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.magtek.com/hardware/card-readers/mms-dyna-devices/dynaprox/documents/programmers-manuals/programmers-manual-commands/commands/echo.md).

# Echo

## Command 0xDF01 - Echo

The host uses this command to prompt the device for a response that contains the same payload it sent.

{% stepper %}
{% step %}

### Sequence of events

* The host constructs the command request for **Command 0xDF01 - Echo** in the format below, populating any of the available parameters with any data. The total length of data to be echoed across all parameters must not exceed 128 bytes.
* The host sends the command request to the device.
* The device sends a command response in the format below to the host, echoing back the exact parameters the host sent in the command request.
  {% endstep %}
  {% endstepper %}

## Table - Request Data for Command 0xDF01 - Echo

<table><thead><tr><th width="267">Tag</th><th width="72.3333740234375">Len</th><th>Value / Description</th><th width="74">Typ</th><th width="75.3333740234375">Req</th><th width="96">Default</th></tr></thead><tbody><tr><td>Beginning of any wrappers, at minimum including <strong>Request Message</strong> </td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>DF01 = <strong>Command 0xDF01 - Echo</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>81</td><td>var</td><td>Data to be echoed</td><td>B</td><td>O</td><td></td></tr><tr><td>82</td><td>var</td><td>Data to be echoed</td><td>B</td><td>O</td><td></td></tr><tr><td>End of any wrappers, at minimum including <strong>Request Message</strong> </td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

## Table- Response Data for Command 0xDF01 - Echo

<table><thead><tr><th>Tag</th><th width="75.33331298828125">Len</th><th>Value / Description</th><th width="75">Typ</th><th width="74.3333740234375">Req</th><th width="98.6666259765625">Default</th></tr></thead><tbody><tr><td>Beginning of any wrappers, at minimum including <strong>Response Message</strong> </td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>DF01 = <strong>Command 0xDF01 - Echo</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>81</td><td>var</td><td>Data being echoed</td><td>B</td><td>O</td><td></td></tr><tr><td>82</td><td>var</td><td>Data being echoed</td><td>B</td><td>O</td><td></td></tr><tr><td>End of any wrappers, at minimum including <strong>Response Message</strong> </td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

## Table - Request Example

{% code title="Example (hex)" %}

```
AA 00 81 04 01 01 DF 01 84 07 DF 01 81 03 01 02 03
```

{% endcode %}

## Table - Response Example

{% code title="Example (hex)" %}

```
AA 00 81 04 82 01 DF 01 82 04 00 00 00 00 84 07 DF 01 81 03 01 02 03
```

{% endcode %}


---

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