Pepper Computer RS485 User Manual

SMART I/O User’s Manual

March 12, 1996

Page 2 - 34

Chapter 2 SMART-BASE

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_POWERFAIL_SET

: The purpose of this operate call is to detect when

(if) the power to the PLC (SMART I/O) has failed.

The function is normally built into the initialization

stage of an application and has the following

syntax :

RetVar := OPERATE(s_time, O_POWERFAIL_SET, 0);

When the application is initialized, the start time is

recorded in battery backed ram (1) at the given

address (

s_time

). If the power to the PLC fails (2)

and recovers at a later stage (3), the software makes

a comparison with the actual clock time (via the

RTC) and the time stored in this memory location.

If a discrepancy exists then the RetVar will record

this fact. Refer to the PEP online help for more

information pertaining to the implementation of this

operate call.

oltage

Time