Hierarchical Menu Systems
Where the specification of a system requires a large number of parameters to be
set, then a PLC based system either requires lots of thumb-wheels, with associated
wiring and I/O hardware, or a general purpose man-machine interface.
The alternative of using a high-level language based control computer can often
provide a better solution than a PLC system, as it can easily be customised to suit
the particular task. This will usually provide a more operator friendly interface than
a PLC system.
A typical system would
have an LCD screen
mounted into the control
panel of the machine.
Below the LCD display screen are five associated keys and a
sixth set-up key. The keys are physically labelled with their
normal function.
However when the [SET-UP] button is pressed, a hierarchical menu tree is entered
and these keys are then used to navigate the menus and to adjust machine
parameters; or indeed to perform any action that may be required by the system
design. This might include printing various production reports or initiating system
diagnostics.
When within the menu tree the screen shows new labels for the keys as shown in
some examples below.
The Set-up Menu is displayed
when the [SET-UP] button is
pressed.
The [UP]/ [DOWN] buttons are used
to point to the required menu item.
Then pressing [SELECT] will then call
up the required screen.
This screen is the result of the
Machine Dwell Menu being
selected from the set-up menu.
From this the machine timing
parameters can be selected.
Having selected the Hammer
Dwell in the preceding menu, this
screen allows the dwell time for the
marking hammer to be adjusted, by
using the [INCR] and [DECR] keys,
followed by pressing [STORE].
The parameter screens always
contains help information and other
details relevant to the parameter
being adjusted.
Often access to some parameters will be restricted to authorised personnel.
Calibration factors are a common example; this can easily be accommodated.
These types of operator interface have been used in the majority of the
applications Quercus Computer Systems has developed for industrial customers.
