Hi, I was starting my university project, and I purchased a "Mei 7900" coin acceptor, and I wanted to connect to it to read information. 
The cable that the coin acceptor brings is the one in the image, from what I found on the internet it works with the RS232 standard, and I think that the colors (black is GND, Brown is VCC, yellow is D+ (RX), blue is D- (TX) )) is correct?
How can I connect these wires to the arduino in order to receive and send the information I need?
Thank you very much 
Your search for RS-232 also showed you the signal is bipolar, meaning it switches from + to - and back for each bit being sent/received. Obviously that cannot be connected to an Arduino pin. So a board/module is necessary to convert the RS-232 to the 5 volts signal that is usable by the Arduino.
Search the internet for RS232 Arduino and see what you find.
Paul
Ok I think I understand what you mean, so you are talking about this module there? 
Thank you very much for your quick reply Paul.
Or, there are RS-232 transceiver chips. Where I work we use MAX232 chips which have been around a long time. It has a built-in voltage-doubler-inverter that generates (about) +10V & -10V (from 5V) for RS-232 Transmission. If you don't need to transmit from the Arduino you don't you don't need to generate those voltages and you should be able to use something simpler.
I've never used RS-232 with the Arduino but usually the tricky thing with RS-232 is getting the baud rate, stop bits, and parity, handshaking, etc., correct.
Another tricky thing is the TX & RX lines. They have to be "crossed" so that TX on one device talks to RX on the other, and the wiring is not always clear. i.e. You can't connect two identical devices together with a "straight cable"... The data (and handshaking lines if used) have to be crossed.
That is exactly what you are looking for.
Paul
Hmmm I was a little confused but I think I got it. So I need the arduino to transmit data over rs232 too.
I just didn't realize it can't connect "can't connect two identical devices together with a "straight cable""
sorry for my bad english 
How do you know it uses RS-232? Do you have another data sheet?
The web site shows a 9 pin connector for RS-232, but the associated data sheet does not even mention it.
Paul
Unfortunately there is no information i think but a person from discord said it was.
I didn't find any information about it other than that there.
But if it's not RS232 what could it be?
Achei esse manual ai
https://manualzz.com/doc/4223877/cashflow-programming-module-cpm-installation-and-user-guide
Your particular machine appears to be one component of a much larger and more complex system.
Paul
ok there is a device to connect the machine to the computer and I looked for something about the device and look what it says
The only way I see for you to be able to use the piece you have is to obtain a service manual for the device. Then you will know the use for each pin on each cable and how to use each pin.
Paul
All existing manuals are already on the internet and I didn't find any talking about pins.
But I will send an email to the company that manufactured these devices, I hope it still exists, and that they can help me.
Find out who does the service on their machines.
Hey Paul, the coin acceptor also has a connection called MDB which works the same, I looked it up on the internet and there is more information about this connection.
You can find dozens of information about pins.
How can i connect this connection to arduino?
Do you have any ideas?
Actually, you do the finding.
Find the data on MDB Receive and MDB Transmit, including voltages and protocol reqires.
Paul
Isn't that what I put the pins information there?
It has 24v, you can't connect directly to the arduino, right?
I think I explained myself wrong, sorry, I didn't want to tell you to look, I meant that there is 1000x more information on the internet about MDB than EXECUTIVE.
Then put the information about pins 4 and 5 right here on the forum for all to see.
