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8 FUNCTION KEYS
For most models, a number of programmable function keys are available. This allows you to assign function keys
to control functionality via the programmable scheme logic (PSL). Each function key is associated with a
programmable tri-colour LED, which you can program to give the desired indication on activation of the function
key.
These function keys can be used to trigger any function that they are connected to as part of the PSL. The function
key commands are found in the FUNCTION KEYS column.
Each function key is associated with a DDB signal as shown in the DDB table. You can map these DDB signals to
any function available in the PSL.
The Fn Key Status cell displays the status (energised or de-energised) of the function keys by means of a binary
string, where each bit represents a function key starting with bit 0 for function key 1.
Each function key has three settings associated with it, as shown:
● Fn Key (n), which enables or disables the function key
●
Fn Key (n) Mode, which allows you to configure the key as toggled or normal
● Fn Key (n) label, which allows you to define the function key text that is displayed
The Fn Key (n) cell is used to enable (unlock) or disable (unlock) the function key signals in PSL. The Lock setting has
been provided to prevent further activation on subsequent key presses. This allows function keys that are set to
Toggled
mode and their DDB signal active ‘high’, to be locked in their active state therefore preventing any
further key presses from deactivating the associated function. Locking a function key that is set to the “Normal”
mode causes the associated DDB signals to be permanently off. This safety feature prevents any inadvertent
function key presses from activating or deactivating critical functions.
When the Fn Key (n) Mode cell is set to
Toggle
, the function key DDB signal output will remain in the set state
until a reset command is given. In the
Normal
mode, the function key DDB signal will remain energised for as long
as the function key is pressed and will then reset automatically. In this mode, a minimum pulse duration can be
programmed by adding a minimum pulse timer to the function key DDB output signal.
The Fn Key Label cell makes it possible to change the text associated with each individual function key. This text
will be displayed when a function key is accessed in the function key menu, or it can be displayed in the PSL.
The status of all function keys are recorded in non-volatile memory. In case of auxiliary supply interruption their
status will be maintained.
Note:
All function key DDB signals are always shown in the PSL Editor. However, the actual number of function keys depends on the
device hardware. For example, if a small 20TE device has no function keys, the function key DDBs mapped in the PSL will not
take effect.
Chapter 14 - Digital I/O and PSL Configuration P54A/B/C/E
308 P54xMED-TM-EN-1