Rs-232C Serial Interface - OKIDATA OL400 Service Manual

Page: 15
Service Guide OL400
Chapter 2 Principles of Operation

2.2.03 RS-232C Serial Interface

The 8251 Universal Synchronous/Asynchronous Receiver Transmitter is used as a controller.
This serial I/F converts serial data received from the host I/F into parallel data for use by the CPU.
It also converts parallel data from the CPU into serial data to be sent to the Host I/F.
READY/BUSY or X-ON/X-OFF are used as the communication protocol between the Host I/F and
OL400. These can be selected through the Menu.
The baud rate, character length, parity check, stop bit, etc., are automatically written into the
82C51 from the menu, so hardware switches are not required.
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