HEIDENHAIN TNC 306 Technical Manual - Manual (Page 416)

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TNC 406/TNC 306 1 Introduction 8-3
1 Introduction
In addition to its CPU (Central Processing Unit), a computer system (for example a PC or controller)
utilizes a wide variety of peripheral equipment such as printers, external memories (floppy disk
drives, hard disks) or other computer systems.
A data interface makes it possible for the CPU and its peripheral equipment to communicate with
each other.
Such communication requires facilities for transferring data to the peripherals. Peripheral device
control and communication via the interface is generally the responsibility of the computer system,
which therefore has to meet certain requirements.
The interfaces, which consist primarily of the physical links between the computer system and the
peripherals, need appropriate software in order to control the transfer of information between the
individual devices. The relationship between hardware and software, which fully defines an inter-
face, is illustrated in the following diagram:
Computer Software Hardware Software Peripheral
e.g. PC,
Controller e.g. Printer,
external memory
Interface
The "hardware" in the diagram includes all the physical components such as the circuitry, pin layout,
electrical characteristics, and so forth. The "software" includes such components as the drivers for
the output modules and is associated with both the operating software of the computer system and
the peripherals.
Due to the wide variety of computers, controllers and peripherals available today, standard
interfaces have been introduced which—ideally—enable widely different types of devices to be
connected to each other.
Standard interfaces include the RS-232-C/V.24 interface which is described in detail later.