Pepper-computer Modular Computers RS485 Bedienungsanleitung PDF herunterladen (Seite 295)

SMART I/O User’s Manual

Chapter 6 Communications Modules

A complete list of the operate COMMANDS may be obtained by selecting a

project from the ISaGRAF projects group, opening an application and

observing the Common defines in the Dictionary pull-down menu. Note that

not all calls in the list may be used within the SMART I/O environment

however, the calls applicable to this module are :

O_INIT_CODE : The syntax and usage have already been explained.

O_SERIAL_READ : This operate call prevents the system from being

blocked due to polling of incoming characters.

Hence, during every ISaGRAF cycle, the program

checks if the buffer for incoming data contains data.

If so, the data will be collected. The syntax is as

follows:

<chars_in> := OPERATE(<ser_in>,O_SERIAL_READ,<chars>);

where <chars_in> represents the actual number of characters

read from the buffer.

<ser_in>

is the input device name.

<chars>

the number of characters expected to be read.

Example

ret := OPERATE(keyboard, O_SERIAL_READ, 10);

If the default value 0D hex is used for the

eor_char

then the scanning of

the input will terminate when either the <RETURN> key is pressed or 10

characters have been read.

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Pepper-computer Modular Computers RS485 Bedienungsanleitung Seite 295