Maple Systems OIT Family (ASCII) - Manual (Page 14)

Sample Status Bit Coil Addresses
OIT Coil Register Address Status Bit
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
Reserved for OIT
Invalid Display Message Number bit
Message/Keytable Error bit
Reset bit
Alarm Stack Full bit
Message Stack Full bit
Message Stack Empty bit
Clear Alarm bit
Clear Alarm Stack bit
Reserved for OIT
Reserved for OIT
Alarm Stack Empty bit
Acknowledge Alarm bit
Reserved for future use
Reserved for future use
Reserved for future use
Invalid Display Message Number
The Invalid Display Message Number status coil is set by the OIT if the ASCII host requests
a non-existent or empty display screen. In systems designed for high integrity, the ASCII
host should clear the coil, then activate an error coil indicating to the outside world that a
problem exists so that the system programmer can correct the programming error either in
the ASCII host or in the OIT.
Message/Keytable Error
The Message/Keytable Error status coil is set by the OIT if it detects invalid or corrupted data
in the display screens or keytable. For instance, this coil will be set if a function key is pressed
that has been configured to display a screen that does not exist. This coil is also set by the OIT
when it detects that the message or function key databases have been contaminated. Since all
of the configuration data is stored in FLASH EPROM, this error should never occur; how-
ever, in the event of a component failure, this coil will indicate that an error has been detected
in the OIT.
Reset
The Reset status coil is set by the OIT every time it powers up or performs a reinitialization
due to exiting the OIT’s local setup menu. This can be used by the ASCII host to indicate that
the OIT performed a reset. The ASCII host can clear the coil and decide what to do with the
information. It is suggested that when this coil is set, the ASCII host reset all I/O to a known
neutral state before clearing the coil and continuing, since the OIT may have experienced a
power down and will not know the current state of the system.
Alarm Stack Full
The Alarm Stack Full status coil is set by the OIT if the OIT’s internal alarm stack is full.
This feature allows the ASCII host to know that, although it may have sent several alarms
to the OIT, nobody is acknowledging them. Additional alarms sent to the OIT cause the
oldest alarm to be eliminated from the stack. Typically, this coil will not be set, but in the
event that it is, a real problem exists: alarms are not being acknowledged by the operator,
either because the alert is not heard or it is too short for an operator to recognize it. The
Alarm Stack Full status coil allows the ASCII host to detect this problem and issue a
OPERATION 13
1010-0088, REV02