Pepper Computer Modular Computers RS485 - Manual (Page 74)

SMART I/O User’s Manual
March 12, 1996 ©1996 PEP Modular Computers GmbH 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.
V
oltage
Time
1 2 3