API Host Initiated Transaction (HIT) Specification

Payment Express exposes a web facing HTTPS service that permits control of a payment transaction on a Payment Express terminal. This functionality is known as a Host Initiated Transaction (HIT). There is no direct physical connection between a HIT Client and the terminal.

Download (HIT) Specification


The HIT Client initiates a transaction request to Payment Express by sending a XML request to the appropriate URL.

Payment Express responds to the request, either immediately or after a configurable timeout period of a few seconds. After the HIT client has received a response, the HIT Client should make a "Status" request and wait for the response. The HIT Client will continue to make Status requests until the Status response indicates that the transaction is Complete (Complete value is returned as "1") in Result.

Status responses from Payment Express may contain instructions for the HIT client to permit information to be displayed for the merchant (DL1, DL2) and enablement of buttons that may be used by the HIT Client to interrupt the transaction or provide feedback (signature capture for example).


POS can communicate with PX Host using HTTPS protocol, see below for endpoint addresses.

UAT (test) endpoint

Address: https://uat.paymentexpress.com/pxmi/pos.aspx

Production endpoint

Address: https://sec.paymentexpress.com/pxmi/pos.aspx

HIT terminal communicates to the Payment Express Host using TCP protocol, see below for endpoint addresses.

UAT (test) endpoint

Address: uat.paymentexpress.com

Port: 65

Production endpoint

Address: scr.paymentexpress.com

Port: 65


IWL 250

The iWL255 is a long range wireless terminal. It is a Mobile handset with full set of payment capabilities, including contactless enabled. It incorporates the latest contact and contactless chip technology. With a colour screen, the iWL255 is able to display more information and detail in an easy to read format. It is a flexible, lightweight, handheld terminal that enables fast, secure, error-free transactions for on the-go merchants.