https://devzone.nordicsemi.com/f/nordic-q-a/1959/can-you-tell-me-master-control-panel-when-service-connection-is-how-some-of-the-dataHello： 1. I used connect Master Control Panel and ble_app_cscs services see the following received some data not understand do not understand, here&#39;s UUID I did not see the program calls? For example： Discovering all attribute UUIDs {&quot;UUID&quot;:10240en-USTelligent Community 13Fri, 21 Mar 2014 16:53:21 GMThttps://devzone.nordicsemi.com/thread/8418?ContentTypeID=1Fri, 21 Mar 2014 16:53:21 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c4f95bd8-697c-46c3-87d6-cd2ed46b0360Ole Morten<p>I&#39;m having some trouble understanding what you want to know, but the UUIDs you see are 0x2800, 0x2803 and 0x2A00, respectively a <a href="https://developer.bluetooth.org/gatt/declarations/Pages/AttributeViewer.aspx?u=org.bluetooth.attribute.gatt.primary_service_declaration.xml">GATT Primary Service Declaration</a>, a <a href="https://developer.bluetooth.org/gatt/declarations/Pages/AttributeViewer.aspx?u=org.bluetooth.attribute.gatt.characteristic_declaration.xml">GATT Characteristic Declaration</a> and the <a href="https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.gap.device_name.xml">Device Name Characteristic</a>.</p> <p>If you wonder which handle a specific attribute has, the easiest is to select it in Master Control Panel and look in the Handle field, as shown in the attached screenshot. For an embedded device, you&#39;ll have to do a full service discovery using the sd_ble_gattc_*_discover() API functions.</p> <p><img src="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/mcp_2D00_handle.png" alt="mcp-handle.png" /></p><div style="clear:both;"></div>