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.