The Isagraf Operate Calls - PEP Modular Computers Modular Computers RS485 User Manual

Chapter 2 SMART-BASE SMART I/O User's Manual

2.7.2 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
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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. A number of these COMMANDS exist for the
SMART-BASE.
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 a SMART-Module is located where the program expects it to
be.
channel provides channel specific information and in the example shown
here, any of the 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.
March 12, 1996 ©1996 PEP Modular Computers GmbH Page 2 - 33