Pepper Computer Modular Computers RS485 - Manual (Page 242)

SMART I/O User’s Manual
March 12, 1996 ©1996 PEP Modular Computers GmbH Page 5 - 86
Chapter 5 Analog Modules
5.3.9.2 The ISaGRAF Operate Calls
Operate calls are built into a program using ST or FBD languages when
defining the project. A typical use could be at the initialization stage to
check that the SMART-Modules are in fact located where they have been
programmed to be. The syntax of the operate call is as follows:
Syntax:
<return variable> := OPERATE(<source var>, COMMAND,
<source data>);
Here the
return variable
is assigned a value associated with the
selected
COMMAND
parameter. Each SMART-Module possesses its own set
of these
COMMANDS
.
Example:
<error.code>:= OPERATE(<channel>, O_INIT_CODE, 0);
O_INIT_CODE
is one of a number of distinct commands recognized by the
PEP Modular Computers’ implementation of board drivers and checks for
example that the board is located where the program expects it to be.
channel
provides channel specific information and in the example shown
here, any of the 8 input channels may be used. The last parameter is not
usually used by PEP implementations and is set to 0 (zero).
The
error.code
returns a value of zero if no error was detected, other-
wise it returns a non-zero value depending on the error encountered. A list of
these error codes may be found in the PEP online help.