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2 the isagraf operate calls – Pepper Computer Modular Computers RS485 User Manual

Page 105

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SMART I/O User’s Manual

©1996 PEP Modular Computers GmbH

March 12, 1996

Page 4 - 17

4

Chapter 4 Digital Modules

4.1.9.2 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

:= OPERATE(, COMMAND,

);

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

:= OPERATE(, 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.

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