I am trying to interface a bill acceptor which provides RS232 (TTL level) with the Arduino's UART.
The manual of the bill acceptor provides the I/O circuit below.
I have tried two ways to no avail.
In the first way, I make the connection with the 2 x 1K resistor and 2n2222 transistor with a breadboard like this:
The RS232 interface of the device has 4 wires: TX, RX, Download VCC (which I connect to Arduino's 5V - I also tried not connecting it, still a bit confused about this wire) and GND (which I connect to common GND with Arduino).
Upon starting up, even from the beginning when not connected with the Arduino, the device flashes in a way that it means its RS232 is not working (by checking with the trouble shooting part of the manual)
Connecting like above also gives the same result.
It's a bit weird to me that the guy who sold me this acceptor, after asking me to try so many ways (checking wires, re-check DIP switches etc.) finally told me that the RS232 interface of the acceptor has to be connected in order for it to work, which is kind of weird to me. I made the above attempts following his claim.
Could anyone tell me where I went wrong? Or is it a defective unit?
Many thanks! Dave