Epson LQ-850X User Manual - Page 205

For all other data transfer conventions, such as word structure or communications protocol, use the information in the manual supplied with your #8143 optional interface. Baud rate selection You can select baud rates from 75 to 19,200 BPS (Bits Per Second). When setting the baud rate, make sure that your printer's input buffer is enabled by setting the LOAD/EJECT button (the beeper sounds twice if the input buffer is enabled), and that you use the bit rate selection table for printers with buffers (in the #8143 interface manual). For more information on the printer's input buffer settings, see Setting the DIP Swtiches in Chapter 3 of this manual. Handshaking timing When the vacant area for data in the input buffer drops to 256 bytes, the printer outputs an X-OFF code or sets the DTR flag to 1 (MARK) indicating that it cannot receive data. Once the vacant area for data in the buffer recovers to 528 bytes, the printer outputs an X-ON code or sets the DTR flag to 0 (SPACE) indicating that it is again ready to receive data. Error handling When a parity error is detected, your printer prints an asterisk (*). All other errors, including framing and overrun, are ignored. 5-56 Using the Printer Options