I am reverse engineering a S-Plus slot machine so, I can control the functionality of the machine. The board has DUART with two custom transciever and recievers. I believe transmitter convert the TTL voltage to RS-232 as the transmitter output 0-8Volts. The problem is the quiescent state of the TTL is High. I believe this state needs to be Low. Does any know if it is possible to invert the Tx and Rx signal on SCN2681 (DUART)


Currently the TTL tx signals HHHHH-DDDDD-HHHHHHH
H = 5V
L = 0;
D = 5->0V / 0->5V

Currently the Tx output signals are HHHHH-DDDDD-HHHHHHH
H = 8V
L = 0;
D = 8->0V / 0->8V

The desire TTL tx signal are LLLLLLL-DDDDDD-LLLLLLL
H = 5V
L = 0;
D = 5->0V / 0->5V