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While the system is operating two packages may come on to the weighing scale if they are close to each other in the package bringing conveyor as shown in the diagram below. If such an incident happen and if the packages fit into the size of the scale both of them will be weighed at the same time and both the boxes will be pushed on to the conveyor carrying incorrect weight packages. The other scenario is when another package comes on to the weighing scale before the previously weighed package is pushed on to the appropriate conveyor. When this happen sometimes the packages may be damaged and the whole system may need to be restarted. Issues mentioned above will definitely cause the system to malfunction therefore the packages need to be fed into the weighing scale at a constant rate such that there will be enough time to weigh and move the package to the appropriate conveyor and also enough time for the pneumatic arm to come back to the original position after before the next package comes on to the weighing scale.
In the program only one weight value is taken from the serial data input to the microcontroller and processed but when practically implementing the system the weight of the package cannot be determined by taking one particular weight value as the reading on the scale may take some time to be stable therefore the program needs to be modified to take at least five weight input values from the weighing scale and average them. Then this averaged value is checked with the specified weight limit and depending on the result the pneumatic arms need to operate.
The surface of the weighing scale needs to be smooth enough to guide the motion of the package to the conveyors on either side.
The pneumatic arm needs to push the package to the appropriate conveyor slowly but in a time efficient manner so that the package would not be damaged or fallen of the conveyor.
The major limitation of the system is that it can only process integer weight values and so it is not suitable for precision weighing. The other thing is that the maximum weight that it can measure is 255g or kg etc. This is because the maximum value that can be saved to a variable is 255 (in decimal) therefore before marketing the product this problem needs to be resolved.
The control unit which has the PIC16F877A microcontroller and the HIN232CP IC must be kept in a less noise atmosphere since external noise interferences can affect the performance of the microcontroller and the IC. Also the noise can affect the performance of the serial data cable so the cable that connects the HIN232CP IC and the COMPIM port needs to be short and efficient.