hi guys, i faced this problem and spend more than 1 week to solve this problem.
I'm trying to communicate an arduino mega 2560 with BV100 note validator(sometimes called bill acceptor). This note validator can support many interface protocol like sio, ssp, pulse, cctalk and many more.
i already read and follow this thread(for BV20 model) in the forum and use the sketch and schematic given, i also setup my BV100 to SIO mode but its not working.
output at serial monitor just 0 when i insert MYR1, MYR5 MYR10 like this:
0
0
0
0
0
0
i also try to print in dec, hec, bin.
when i change the baudrate in sketch and at monitor to 300, weird words showing on serial monitor.
i'm sure that i've follow the schematic correctly. Common ground connected.
this my schematic:
https://drive.google.com/open?id=0B3c_VPBO9Qq3NFd4MlRmbXlneVE
and this BV100 note acceptor user manual:
https://drive.google.com/open?id=0B3c_VPBO9Qq3UXVvZWF1MHlUYkE
page 8 --> protocol that available on BV100
page 10 --> connector pins detail
page 18 --> detail about SIO protocol on BV100
Can someone guide/explain/ give me clue how to use this protocol (SIO). and how to coding to receive and transmit the data to this note validator using this protocol?
i'm not really good in communication protocol 
hope someone can help me finish this project. sorry for my bad english
here the codes i use:
void setup()
{
Serial.begin(9600);
}
void loop()
{
if( Serial.available() > 0)
{
Serial.println(Serial.read());
}
}