From the start of the project, TWI took an active lead with respect to the integration of the four prototype inspection modules. One of the first efforts as part of development of the Microscan system was to get all partners to agree and work to common standards. Given the scope of the project and time restraints it was considered unrealistic to combine the inspection modules using a complex hardware and software scheme. Instead an agreement between the partners was made early on in the project to use IPC's SMEMA common standard for electronic boards material handling systems.

Each inspection module in the system is designed to operate in a pull configuration for easy integration with another inspection module or other equipment on standard electronics manufacturing lines. Through utilisation of two signals "Machine Ready" and "Board Available" transport of a PCB from one inspection module to another does not take place until called by the next downstream node.

Each module in the system is designed to operate in pull configuration for easy integration with another inspection module or other equipment on standard electronics manufacturing lines. (Pull systems mean the board will not leave a module until called by the next downstream node, eliminating the need for a separate cell controller for each node on the production line.) Each inspection module has been designed so that a pass or failed component is indicated by an alarm, an on screen flag, and an entry saved to a results file local to each prototype. In addition each inspection prototype PC has the capability to be networked via 10/100 Ethernet, thus allowing a remote operator to interrogate all the prototype results files for statistical analysis from a single PC connected to the network.

Each module is controlled by a host PC. A common Input/Output (I/O) board was developed by TWI to facilitate a standardised electrical interfacing scheme for each inspection module. The I/O board accepts signals to/from the PC either via USB, RS232 or PCI bus. The I/O module provides the signals for machine-to-machine communication and control of the conveyors. Figure 1 shows an overview of the final prototype indicating the signals used in the system.

Fig.1 Prototype System Overview combining the four inspection modules

For cost reasons, and because a proof in principle prototype was being developed rather than a product for immediate launch into the commercial market, only the minimum SMEMA mechanical equipment interface standards were adopted for the conveyor designs as detailed in Table 1.

Conveyor Height	Each machine shall have the transport conveyor height adjustable from 940 to 965 mm from the floor to the bottom of the PCB.
Fixed Rail	For the purpose of the SMEMA standard, the front rail is defined as the fixed rail.
Conveyor Width	The rear rail is adjustable to accommodate different sized PCBs.
Edge Clearance	The conveyor should not require no more than 5mm of clear board space at the side edges.