Chapter 5: Communication; Communication Overview; Interface; Sending Commands - NCR 7156 Owner's Manual

7156 Owner's Guide

Chapter 5: Communication

Communication Overview

In order for a receipt or slip to be printed, a program must be in place that translates the
data from the host computer into a language that the printer can understand. This program
must tell the printer exactly how to print each character. This chapter describes how to
create such a program or modify an existing one.

Interface

In order for the printer to communicate with the host, a communication link must be set
up. The 7156 supports the industry standard RS-232C communication interface. This
interface has a protocol associated with it that the host computer must understand and
adhere to.
Only when the interface parameters are matched and the proper protocol is used will the
host and the printer be able to communicate. See the section, "RS-232C Interface" on the
next page for a description of the protocol associated with the RS-232C interface.

Sending Commands

Once the communication link is established, commands can be sent to the printer. This
section describes how to send commands to the printer using DOS and BASIC. This section
does not take into account the necessary protocol, but is meant as a general introduction to
how the printer functions.
Using DOS to Send Commands
One way of getting commands to the printer is to send them directly from DOS. For
example, the command
COPY CON: COM1:
sets the computer up such that the Hex code corresponding to any key that was pressed
would be sent to the RS-232C communication port COM1 when the COPY mode is exited.
If the printer is connected to COM1, then the data will go to the printer.
Exit the COPY mode by typing
CTRL Z
and then pressing the ENTER key. Once the computer knows to direct data from any print
command to the proper port, commands can be sent from any software program.
Chapter 5: Communication
September 1997 49