Set Up the PAX A800 With Commerce Engine

Description: Learn how to unbox, activate, and connect your PAX A800 to the Shift4 platform using Commerce Engine.

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Overview

The PAX A800 is a portable wireless payment device with a 5.7-inch touchscreen, integrated printer, and support for tap, insert, and swipe transactions. It runs Commerce Engine and connects to the Shift4 platform over Wi-Fi or cellular.

Unbox the Device

1. Check the shipping box for signs of tampering.
2. Confirm the following items are present:
   • One PAX A800 payment device
   • One wall outlet power supply with USB-A port
   • One USB-A to USB-C charging cable
   • One paper roll
   • One micro SIM card (cellular configurations only)
3. Inspect the device for physical tampering. Check the card slot and magnetic swipe reader for foreign objects.

Warning: If any inspection fails, contact Shift4 Support immediately and do not proceed with setup.

Charge the Device

1. Connect the USB-C charging cable to the port on the back of the device.
2. Connect the USB-A end to the wall adapter.
3. Plug the adapter into a power outlet.

Insert a SIM Card (Cellular Only)

1. Place the device face down on a flat surface.
2. Remove the back cover by pressing the latch and lifting.
3. Open the metal latch on one of the two upper SIM slots by sliding it gently.
4. Place the SIM card contacts-down, aligning the clipped corner with the mold.
5. Lower the latch, press, and slide to lock.
6. Replace the back cover.

Important: The A800 requires a micro-size SIM. If using a tri-cut holder, remove the correct size before inserting.

Power On the Device

Press and hold the power button on the lower-left side of the device for three seconds. Commerce Engine launches automatically.

Note: If the device does not power on, visit the PAX A800 Will Not Power On article.

Activate the Device

Note: Before starting activation, confirm the device is charged to at least 50% and that you have either Wi-Fi credentials or a SIM card ready.

Commerce Engine will guide you through language selection, network setup, and software download. This process takes approximately 15–20 minutes and may include automatic reboots. When activation completes, the device displays the black Shift4 idle screen and is ready to accept payment requests.

For the full activation walkthrough, visit the Set up Commerce Engine Devices article.

Connect to Your POS

How the A800 connects to your POS depends on your integration type.

• On-premise: Your POS sends payment requests directly to the device's IP address. Use port 8085 for S4 REST or port 8084 for OPI. The device must have a static IP address.
• On-device: The POS application runs directly on the device alongside Commerce Engine. Payment requests are routed locally without requiring a network connection between the POS and the terminal.
• Cloud: Your POS sends requests to the Shift4 Cloud rather than directly to the device. Confirm that your POS application includes the correct device parameters in each request — specifically device.manufacturer and device.serialNumber — and that it can reach the Shift4 Cloud endpoint. No static IP is required.

Consult your POS vendor's documentation for specific connection steps.

For day-to-day device operations, visit the Use the PAX A800 With Commerce Engine article.