GE GFK-0787B User Manual

tModular Redundancy Flexible Triple Modular Redundant (TMR) System 

The GMR system can optionally use the standard Series 90-70 I/O Point Fault references.

The I/O Point Faults feature allocates a bit reference for each potential discrete point
fault and a byte reference for each potential analog point fault.

Note that space for these references is taken from the space available for the application
logic.

With I/O Point Faults enabled, when a fault occurs the fault reference (IO_FLT) is set.
The [FAULT] and [NOFLR] contacts can be used to access the point fault.

Point fault data is written to the references at the start of each CPU sweep, so they
always contain the most recent data.

The use of I/O point faults requires the following setup during Logicmaster 90
configuration:

A. During CPU configuration, select Memory Allocation and Point Fault Enable (F4)

from the CPU Configuration menu.

B. Change the Point Fault Reference setting from DISABLED to ENABLED.

When the GMR system diagnoses a discrete I/O fault, it logs the appropriate faults in its
fault tables and set the appropriate fault contacts.  For certain types of discrete I/O faults,
the system allows a predefined amount of time for the problem which has caused the
fault to be repaired.  If it is not rectified within this period of time, an I/O shutdown of
the I/O which corresponds to the block(s) occurs, unless I/O shutdown is disabled by the
cancel I/O Shutdown control bit (%M12265).   I/O shutdown is defined as setting the
affected I/O to its safe state.  For more information about I/O Shutdown, please refer to
page 4-18.

To be aware of a pending I/O Shutdown, monitor Status Bit %M12244  (IO_SD).

To completely prevent an I/O Shut Down from occurring set Control Bit %M12265
(SD_CAN).