What are the security aspects of the payment terminal?

Question

Payment systems

Good afternoon. We are developing software for a payment terminal and, due to the lack of a specially trained person, we are trying to formulate all the points related to the safety of his work. Terminals are designed to pay for the services of only one organization and will not be designed to work with all cards, but only with cards of this company
At the moment, we have come up with the following:
- Handling errors of terminal devices (bill acceptor, printer, etc.)
- Blocking the card after several incorrect pin codes
- Actions when the Internet
is interrupted - Logging everything that happens
- Binding software to the terminal
- Handling cheating
- Security sources
And that's it. If anyone has dealt with a similar issue, please suggest the missing items.

Answer 1

what country are you from? we have a dude, the head of the security department of the department for working with ATMs. deals with these issues.

Answer 2

Hmm... but how do you develop software for an ATM without communicating directly, for example, with processing directly involved in ATMs?
because
The card is blocked not by an ATM, but by processing
Then if you make ATM software, it must be compatible with existing processing software (OpenWay for example)
And read the PCI DSS standard