Maple Systems OIT Family - Manual (Page 24)

Key Coils
There are three types of coils in the PLC that are used to pass keypress data from the OIT
to the PLC: Control Key coils, Function Key coils, and Screen Dependent Function Key
coils (SDF keys are only available on the OIT3100 Series, OIT4100 Series and
OIT5400B).
Control Key Coils
Each key on the OIT (except function keys) can be configured to perform its normal OIT
action and/or set a PLC coil. If the OIT Action function is enabled, the key performs its
normal OIT action (for example, the ALARM ACK key acknowledges the current
alarm). If the PLC Coil function is enabled, pressing the key sets the corresponding
Control Key coil in the PLC and releasing the key clears the coil. If both functions are
enabled, the key performs its normal OIT action and sets/clears its Control Key coil in the
PLC. If both functions are disabled, the key does nothing. Each non-function key can be
configured independently using the OIT Control Key Editor in OITware-200 (from the
Configuration menu, choose Keyboard Settings, then choose Control Key Editor).
NOTE:Be careful when disabling a key’s normal OIT action, since the key no longer performs
its primary function once configured this way.
In order to use the PLC Coil function, a starting PLC address must be configured in the
OIT Control Key Editor in OITware-200 (from the Configuration menu, choose
Keyboard Settings, then choose Control Key Editor). Each non-function key is
automatically mapped to a particular offset PLC coil from this starting address:
The PLC coil function is most often used to configure a non-function key to be used for
some purpose defined by the system programmer. For instance, if the LAST MESSAGE
and NEXT MESSAGE keys are not being used to display a history of messages, then
they can be programmed as momentary switches. The PLC coil function can also be used
to notify the PLC when the OIT operator has pressed one of the non-function keys.
Read more about the OIT Control Key feature in Chapter 6: Key Types under the
Control, Edit & Numeric Key Coils section.
Function Key and Screen Dependent Function Key Coils
Each global and screen dependent function key on the OIT has a corresponding coil in
the PLC. When the function key is pressed, the coil in the PLC is activated. When the
coil is cleared depends on how the function key is configured (for more information on
clearing the coils, refer to the Function Key sections in CHAPTER 6: Key Types).
How the Function Key and Screen Dependent Function Key coil addresses are assigned
depends on the OIT model. The OIT3100 and OIT4100 Series allow each global or
screen dependent function key to be assigned a unique PLC coil address. The other OIT
models only allow the starting PLC address for each set of coils to be assigned. The
Function Key coil address(es) is assigned in the Function Key Editor dialog box (from
the Configuration menu, choose Keyboard Settings, then choose Function Key Editor).
The Screen Dependent Function Key coil address(es) is assigned in the
Screen-Dependent Function Key Default Actions dialog box (from the Configuration
menu, choose Keyboard Settings, then choose Screen-Dep. Screen Editor).
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