7
C O N T R O L L E R S T R U C T U R E
The P280 is constructed around a Micro Controller chip and the rest of the electronic components are only to
support the chip. The physical boards and their components are referred to as HARDWARE and the program
that operates the controller and resides in the chip is called the SOFTWARE. The variables which make up the
weld schedules are stored in MEMORY and can be viewed and/or changed. There are two clocks in the system.
One clock is crystal controlled and operates at 4 million cycles per second and is the time base for all the welding
functions.
The SOFTWARE has been written to operate in a fixed manner and must use the values that the
programmer/operator has placed in the weld schedules. A weld schedule may contain up to 15 variables and
there are 100 possible schedules. So, with 100 schedules and 15 variables, there has to be 1500 memory locations
or boxes, where a number or command can be kept.
The SOFTWARE will allow the operator to look at the contents of any box, or memory, and leave it alone or
change the controls. When the controller has been placed in the WELD schedule position (Home) and the
footswitch first stage is depressed, the control will move to the SQUEEZE mode. It will use the value in that
memory location to set the timer. NOTE: The SQUEEZE function is pre-set at (2).
When the second footswitch stage is depressed, the software will sequence through each step using the values
found in each appropriate box.
Three other variables that are stored for each schedule are REPEAT, WELD and SEAM. Repeat is used in spot
welding mode when automatic repeating is used for rapid consecutive welds by holding down the footswitch.
Weld, and therefore, No Weld, can be used for sequencing the control, checking weld pressure, material
positioning and timing without weld current. Seam will force the control to use Squeeze and then cycle through
the Cool/Up Slope/Heat Down Slope sequence continuously until the footswitch is released. At this point, the
Hold and Off will complete.