Heidenhain SHB Data Interfaces for HEIDENHAIN Manual de usuario descargar pdf (Pagina 6)

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2 General Information on the Data Interfaces

2.1 RS-232-C/V.24 Interface

RS-232-C is the designation of a serial interface for transfer rates of up to 19,200 bps based on

the American EIA standard of the same name. Data transfer is executed asynchronously, with a

start bit before each character and one or two stop bits after each character.

The interface is designed for transmission distances of up to 30 meters.

The RS-232-C interface has been adopted with slight modifications and introduced into Europe

as the V.24 interface. The relevant German standard is DIN 66020.

2.1.1 Hardware

The physical connection between two RS-232-C/V.24 interfaces is an asymmetrical line, i.e. the

common ground connection between transmitter and receiver is used as a return wire.

Physical connections:

2.1.2 Signal levels

With the RS-232-C/V.24 interface one must differentiate between two different signal lines and

their levels.

Data lines:

The data signals are defined as being logical one (MARK) over the range –3 V to +15 V and

logical zero (SPACE) over the range +3 V to +15 V.

Control and signal lines:

These signals are defined as being ON (High) over the range +3 V to +15 V and as OFF (Low)

over the range –3 V to –15 V.

For all of the signals, the voltage range from –3 V to +3 V is not defined as a logic level and can

therefore not be evaluated.

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Heidenhain SHB Data Interfaces for HEIDENHAIN Manual de usuario Pagina 6