Connect to credit card reader

Okay, so I am getting close to ready to deploy my custom Point of Sale interface for our shop and now am getting into territory I have zero experience with.

I have an existing POS that is just that… a POS and it doesn’t fit our needs and honestly I don’t want to pay someone to go round and round to get what I want after 20 iterations and a bunch of crap I didn’t ask for. Hence why I am writing my own.

The next phase is communicating with the credit card terminal in that when I ring up a transaction and select credit card payment, the data required to initiate the terminal transaction is pass to the credit card reader. I am not sure where to start on this.

The base system is Linux Mint 19.3 Cinnamon on a 15" touch screen HP Laptop. On top of course is the Point of Sale system I am writing. It’s a stand alone system as we are a small shop and have no current of foreseeable need to have a server for more than one terminal.

I have almost all aspects completed with a few left to test, but I need to get the credit card side done now so that when I finish testing I can scrap the EPOS I have and start using ours.

So… who here has a lead or information that can help me with my endeavor?

You’ll have to get the details from your Terminal. For example we worked on a PayJunction system which requires calling a REST API that activates the terminal (with amount). You then wait a minimum of 4 seconds to start polling (again another API call) and wait for the terminal to have completed the sale, sent it to their website. At that point it’s complete and you can ask for amount or any errors. Payjunction has a website dedicated to all this. AFAIK, most of them are similar.

Thank you I’ll start making some calls!

Hello John

Welcome to PCI (Payment card industry) compliance! Not! From my experience with E-payments (credit card, etc.) it’s not fun at all. Everything is regulated. I went through the transition from magnetic strip to chip. I started updating my software and found out that it has to be PCI certified because my software would handle credit card information. $$$ Long story short and to the point. I would recommend TranSafe UniTerm (Monetra). They support Linux. (other systems too)

This one example (Please read their website other options) : Your software talks to UniTerm asking for E-Payment. Then UniTerm communicates to credit card machine. Uniterm handles all credit card function. Sends back to your software ok or not. You need understand theirs so many regulations when it comes to E-Payments. The credit receipt are regulated too. The Uniterm can print you credit receipt. Uniterm very flexible. You can run it local or in the cloud with TranSafe Gateway.

Do keep credit card information on you system or not? I recommend you don’t. But if you do your software have to meet PCI Security Standards. (That was about 4 years ago when I looked in to it.)

My experience is on Linux system with a Point of Sale system written in C. For development testing I use Ingenico iSC Touch 250. All you software need to do is open Ethernet port to Uniterm and talk to it.

Happy Coding! :slight_smile:

No, I don’t keep credit card information. Don’t need that legal hassle added to all the other crap I deal with in California.