Pepper Computer Modular Computers RS485 - Manual (Page 295)

SMART I/O User’s Manual
©1996 PEP Modular Computers GmbH March 12, 1996 Page 6 - 13
Chapter 6 Communications Modules
6
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.