In the documentation in A10_Thunder_AX_271-P2_SLB_ADC-2013.08.05 it was explained on page 878 and 879.
USING THE GUI 1. Select Config Mode > SLB > Service > SSL Management, if not already selected. 2. On the menu bar, select Certificate. 3. To export a certificate: a. Select the certificate. (Click the checkbox next to the certificate name.) b. Click Export.
USING THE CLI To export a certificate and its key, use the following commands at the Privileged EXEC or global Config level of the CLI: export ssl-cert file-name url export ssl-key file-name url