{block name="sub_menu"}
        {if $navdata = $modx->runSnippet("pdoMenu", [
                'parents'   => $modx->resource->parent,
                'level'     => 1,
                'where' => json_encode([
                    "isfolder" => 1
                ])
        ])}
            <nav class="sub-menu">{$navdata}</nav>
        {/if}
{/block}