Card machine quick guide
How to use our card machines (PAX A920) and their docks the right way — and the two things you must never do. No technical knowledge needed.
The two golden rules
If you remember nothing else, remember these.
Keep each machine on its own dock
Every card machine is paired to one dock. They share a matching shape and number — the ★1 machine goes with the ★1 dock, the ■2 machine with the ■2 dock, and so on.
Never unplug the dock's power
The dock is the bridge between the machine and our system. While it's plugged in, payments flow automatically. With no power, nothing works.
Meet your kit
Three things to recognise — the machine, its dock, and the matching labels. Tap a photo to enlarge.
PAX A920
The handheld you tap, insert or swipe cards on. Each one has a shape + number label on top.
PAX L920-BE
Sits on the counter, stays plugged in, and connects the machine to our network and Sentec POS.
★ ■ ▲ ●
Star, square, triangle, circle. The machine and its dock always share the same shape and number.
How it works, in one minute
You don't need to set anything up — it's all done. Here's the picture so the rules make sense.
1 · The machine talks to its dock — wirelessly
Each machine connects to its own dock over the dock's Wi-Fi hotspot and Bluetooth. Both are named after the dock's serial number — for example L920_1230459845. Keep the machine within about 5–10 metres of its dock (same counter or area).
2 · The dock is the bridge to our system
Each dock is plugged into the hotel network by an Ethernet (LAN) cable, and into the front-desk PC. That's how a card payment is sent straight into Sentec POS and Sentec PMS — no typing required.
The dock must stay plugged into power3 · The card details land in Sentec POS & PMS automatically
Take the payment as normal and it's captured for you. Place the machine back on its dock to charge — it doesn't have to sit there all the time, just stay near its own dock.
Find the matching pair
Match the shape and the number. A machine only works fully with its own dock.
Same shape, same number. ★1 ↔ ★1. Never mix them.
| Tag | Where it is | Its dock — Wi-Fi / Bluetooth name | Terminal PIN |
|---|---|---|---|
| ★1 | Reception | L920_1230459845 | 2246 |
| ■2 | Reception | L920_1230459861 | 2246 |
| ▲3 | Lv2 Lemongrass (Level 2) | L920_1230459858 | 2498 |
| ●4 | Art & Soul Cafe | L920_1230824349 | 2498 |
Taking a payment
You start in Sentec POS — the terminal fills in the amount for you.
In Sentec POS, ring up the items and tap Payment.
The terminal wakes up and shows the amount automatically, then asks to present the card. A 60-second countdown starts.
The guest taps, inserts, or swipes within 60 seconds. Enter the PIN if prompted, then hand the machine back.
Wait for the green Authorised screen — the receipt prints. Place the machine back on its own dock.
If a machine is switched off and on, the bank app shows a brief pop-up: "ECR connection succeeded." That's your sign it's linked to its dock and ready to take card payments.
A successful payment ends on the green Authorised screen, then prints the receipt.
No "ECR connection succeeded" after a restart, or payments keep failing? Check the machine is on its own dock and the dock is plugged in — then tell IT.
New to the terminal? Try the full payment flow on a practice terminal in your browser — no real card needed.
Common mistakes we've seen
Both of these have already happened here — and both stop card payments.
Terminals swapped between locations
A machine was moved to a different counter and placed on another dock. It charged, but payments stopped reaching the system — because it was away from its own dock.
The dock was unplugged
Someone unplugged the dock's adapter (or borrowed its charger for a phone). Card payments stopped completely until it was plugged back in.
If anything looks wrong, contact IT — don't try to fix it by swapping machines or docks.
Do & Don't
The short version you can pin up next to the till.
- Keep each machine with its matching dock (same shape + number).
- Leave every dock plugged into power and connected.
- Put the machine back on its own dock to charge.
- Tell IT if a machine won't connect, or a label is missing or peeling.
- Swap or move machines between docks or locations.
- Unplug a dock, or take its charger for another device.
- Move a machine to another area without asking IT first.
- Peel off, cover, or change the shape labels, or change any settings.
What happens if…
So you know what you're seeing — and how to fix it.
It will charge, but it's now away from its own dock, so it can't reach Sentec POS or PMS. Move it back to its matching dock and payments work again.
The machine loses its bridge to our system. No card payments go through until the dock is plugged back into power and connected. Plug it back in, then tell IT.
The terminal cancels that attempt. Just start the payment again from Sentec POS and present the card within the countdown.
Quick questions
Tap a question to open the answer.
Does the machine have to stay on the dock all the time?
No. Just keep it near its own dock (within about 5–10 m). The dock only needs to stay powered and connected. Place the machine back on the dock when the battery gets low.
Can I use any machine on any dock?
No. Each machine is set up to work only with its own matching dock and the PC behind it. On any other dock it will charge, but card payments won't reach the system.
How do I start a payment?
Ring up the sale in Sentec POS and tap Payment. The terminal automatically shows the amount and asks for the card — you don't type the amount on the terminal. To cancel, press Back on the terminal.
How do I know the connection is OK?
Switch the machine off and on. The bank app shows a brief "ECR connection succeeded" message — that means it's talking to its dock and our system. If you don't see it, tell IT.
A label fell off and I can't tell which machine goes where.
Don't guess. Contact IT to re-check the pairing and re-label it. Using the wrong pair just leads to failed payments.
The terminal looks faulty or shows an error. Who do I call?
Tell IT first. For hardware faults, IT contacts GHL (NTT Data) on 03 6286 5222 with the terminal's serial number and TID/MID ready (see the support section at the bottom).
How do I reprint a receipt?
On the terminal, go to Menu → Transaction → Reprint. You can reprint the last receipt or search by reference number. The guest copy prints first, then the merchant copy.
Technical reference
For IT and the curious — most staff can stop above.
Connection architecture & systems
Software on the terminal
- Bank app
- PayHereDirect UOB
- Firmware
- ~v01.00.37
- Android
- 7.1.2
- ECR service
- PS. Demeter
Hotel systems
- POS
- pos.sentec.io
- PMS
- pms.sentec.io
- Acquirer
- UOB / GHL
The PS. Demeter ECR service must be running for POS integration. After a terminal reboot the bank app confirms "ECR connection succeeded." Our POS is Sentec POS and reception runs Sentec PMS.
RS232 wiring — RJ45 (T568B) → DB9 female
| DB9 pin | Signal | RJ45 pin | Wire colour |
|---|---|---|---|
| Pin 1 | DCD | Pin 7 | White / Brown |
| Pin 3 | TXD | Pin 5 | White / Blue |
| Pin 4 | DTR | Pin 6 | Green |
Equipment register — the 4 labelled pairs
| Tag | Location | Terminal S/N | TID | MID | PIN | Conn. | Dock S/N (= SSID/BT) |
|---|---|---|---|---|---|---|---|
| ★1 | Reception | 0822761676 | 22343950 | 147377 | 2246 | Ethernet (LAN) | 1230459845 |
| ■2 | Reception | 08227633044 | 22343951 | 147377 | 2246 | Ethernet (LAN) | 1230459861 |
| ▲3 | Lv2 Lemongrass | 0822763746 | 21343716 | 1010002498 | 2498 | Ethernet (LAN) | 1230459858 |
| ●4 | Art & Soul Cafe | 0822763741 | 21343717 | 1010002498 | 2498 | Ethernet (LAN) | 1230824349 |