function getStatus($orderId)
{
    $config_info = parse_ini_file('paGateway.ini', true);
    $uid = $config_info['login']['uid'];
    $pass = $config_info['login']['pass'];
    // PO Number entered via API. Use Magento Invoice ID.
    //$_orderId = "100000043";
    $order = new paOrder();
    $order->setUser($uid, $pass);
    $order->setPoNumber($orderId);
    $obj = $order->sendRequest();
    //response is JSON object
    //get the response
    $response = json_decode($obj, true);
    $OrderStatus = array();
    if ($response) {
        if (array_key_exists("responseStatus", $response)) {
            if ($response["responseStatus"] == "Failed") {
                //PO number was wrong or response failed for some other reason
                echo "Response failed \r\n";
                $log->lwrite("Response failed while checking order status at PA. Order# " . $orderId . " ResponseDetail: " . $response['responseDetail'] . "\r\n");
                $OrderStatus['Status'] = "Failed";
            }
        }
        //prepare array to return
        $OrderStatus['Status'] = $response[0]['Status'];
        $OrderStatus['TrackingNumber'] = $response[0]['TrackingNum'];
        $OrderStatus['Time'] = $response[0]['entryTime'];
    }
    return $OrderStatus;
}
function getStatus($orderId)
{
    $config_info = parse_ini_file('paGateway.ini', true);
    $uid = $config_info['login']['uid'];
    $pass = $config_info['login']['pass'];
    // PO Number entered via API. Use Magento Invoice ID.
    //$_orderId = "100000043";
    $order = new paOrder();
    $order->setUser($uid, $pass);
    $order->setPoNumber($orderId);
    $order->sendRequest();
    //response is JSON object
    //$ret = json_decode($order->sendRequest(),true);
    return $order->sendRequest();
}
<?php

require_once "paOrder.php";
$order = new paOrder();
$order->setUser('username', 'password');
$order->setPoNumber('PP-0509-51341137F7729505S');
$order->sendRequest();
//response is JSON object