SERIAL INTERFACE

Pin No   Signal                     Direction     Description                                              
                                                                                                           
1        Frame Ground                             Frame gound                                              
                                                                                                           
2        Transmit Data              Output        data from the printer to the host                        
                                                                                                           
3        Receive Data               Input         data from the host to the printer                        
                                                                                                           
4        Request To Send            Output        space when printer is ready to transmit data             
                                                                                                           
5        Clear To Send              Input         space when printer is ready to receive data              
                                                                                                           
6        Data Set Ready             Input         space when host is on and ready                          
                                                                                                           
7        Signal Ground                            signal ground                                            
                                                                                                           
8        Carrier Detect             Input         space when the host is ready to send data                
                                                                                                           
11       Reverse Channel            Output                                                                 
                                                                                                           
20       Data Terminal Ready        Output        space when printer is on and ready                       
                                                                                                           

Space = + 3volts or higher

Mark = -3 volts or lower