my_pos 0.3.1

Kasseneck's Flutter plugin for Android Smart POS terminals: card payments, receipt printing and the RKSV signature card (SAM) for Austrian cash registers.

my_pos

Card payments, receipt printing and the RKSV signature card on Android Smart POS terminals.
The terminal bridge of Kasseneck, the cloud cash register system for Austria.

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my_pos connects a Flutter app to an Android Smart POS terminal: take a card payment, print the receipt on the built-in printer and sign receipts with the RKSV signature card in the terminal's SAM slot. It runs in production in the Kasseneck apps, for example the taxi register Karteck.

💳 Card payment	Opens the terminal's payment screen and returns the full result (approval, reference number, STAN, card brand, ...)
🧾 Receipt printing	Text, two-column lines, images and QR codes on the built-in printer
🔏 Signature card	Certificate serial and signature with the RKSV signature card in the SAM slot (ACOS, ACOS-ID, CardOS)
📱 Tap to pay	Payments through the Glass app on a phone

Android only. The app has to run on a supported terminal (or with the Glass app installed).

Installation

dependencies:
  my_pos: ^0.3.1

Nothing else to set up: the plugin adds the package queries for the terminal's payment service to the merged manifest. Minimum Android version is 6.0 (API 23).

Card payment

import 'package:my_pos/enums/my_pos_currency_enum.dart';
import 'package:my_pos/my_pos.dart';

final result = await MyPos.makePayment(
  amount: 12.50,
  currency: MyPosCurrency.eur,
  printCustomerReceipt: false, // the app prints its own receipt
  printMerchantReceipt: false,
  reference: 'ORDER-4711',
);

if (result.isApproved) {
  // Paid. Keep result.reference_number / result.STAN for the books.
} else if (result.isUnknown || result.isCancelled) {
  // No approval came back. Check the terminal's transaction list
  // before charging again: the card may still have been charged.
} else {
  // Declined: result.response_code says why.
}

Only isApproved means paid. A missing result (isUnknown, or isCancelled after the payment screen was closed) does not prove that no money moved.

makePayment throws a PlatformException only when the payment screen cannot be opened:

Code	Meaning
NO_ACTIVITY	The app is not in the foreground.
ALREADY_ACTIVE	A payment is already running.
INVALID_ARGUMENT	Amount is not a positive number, or the currency is missing.
PAYMENT_NOT_STARTED	The payment service is missing or refused the request (unknown currency, unsupported function, ...).
RESULT_LOST	The app's activity was closed for good while the payment ran. Check the terminal.

Only one payment runs at a time, and every call is answered exactly once.

Receipt printing

import 'package:my_pos/enums/my_pos_print_response.dart';
import 'package:my_pos/models/my_pos_paper.dart';

final paper = MyPosPaper()
  ..addText('Kasseneck', fontSize: 32, alignment: PrinterAlignment.center)
  ..addDoubleText('Taxi ride', 'EUR 12,50')
  ..addDoubleText('Total', 'EUR 12,50')
  ..addQrCode('https://kasseneck.at', size: 240)
  ..addSpace(2)
  ..addCutLine();

final status = await paper.print(); // success, failed, outOfPaper or unknown

Printing never throws. On a device without the print service the answer is PrintResponse.failed at once; if the terminal does not report back within 60 seconds it is PrintResponse.unknown. An image or QR code that cannot be built is left out, the rest prints. paper.toString() gives a text preview for logs and tests.

Signature card (RKSV)

Austrian cash registers sign every receipt (Registrierkassensicherheitsverordnung, RKSV). On a Smart POS terminal the signature card sits in a SAM slot:

import 'package:my_pos/enums/sam_slot_enum.dart';

final serial = await MyPos.getCertificateSerialHex(SamSlot.slot_1);
final signature = await MyPos.doSignature(dataToBeSigned, SamSlot.slot_1, pin);
// Base64url without padding, ready for the RKSV signature value.

doSignature hashes the data with SHA-256 before signing. Errors come as PlatformException with the code NO_SAM (no card in the slot) or ERROR_SIG.

Publishing to the terminal app store

Terminal apps are installed from the terminal vendor's app store, not from Google Play. What helped us get through the review:

• Ship 32-bit ARM (armeabi-v7a) next to arm64-v8a. Some terminals run a 32-bit system and cannot install an app with 64-bit libraries only.

  defaultConfig {
      ndk { abiFilters "armeabi-v7a", "arm64-v8a" }
  }
  

• Upload a release APK signed with APK Signature Scheme v2 and keep the same key for every version.
• Ask only for permissions the app needs; the review checks them.

Example

example/ charges EUR 1.00 and prints a test receipt.

About Kasseneck

Kasseneck is a cloud cash register system (Registrierkasse) for Austria: RKSV-compliant receipts from the browser, the phone or the card terminal, without extra cash register hardware. This plugin is how Kasseneck talks to card terminals.

• 🌐 Kassensystem: kasseneck.at
• 🏢 Built by Kreiseck Software Solutions, Austria
• 💙 If this package saves you time, a like on pub.dev helps.

Versioning

Semantic versioning, see the CHANGELOG.

License

Apache-2.0, see LICENSE. © 2023-2026 Kreiseck Software Solutions.

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_{Made with care by Kreiseck Software Solutions for Kasseneck · Austria 🇦🇹}