Functional Test - Go - NoGo Testing

• Put simply, the Go / NoGo method involves testing a module or unit (sometimes referred to as a Unit Under Test – UUT) to see if it is working (Go) or not working (No Go).
• All Diagnosys systems perform functional testing on modules or UUTs.
• Sometimes this type of testing can be challenging. The test code is written and sequenced to prove the unit works to a pre-determined set of conditions. Producing the test program for a unit requires an understanding of its function, or a test specification and sequence, such that the test code can be produced and written manually. There is no alternative and this process will take a finite time.
• When a unit fails this testing process, the task turns to diagnosing the cause of the failure so that remedial work can be performed.

This technique applies and measures signals to a module or circuit. The input signals are created by the programmer and the output can be manually predicted, learnt from a known good circuit or may be taken from a logic simulator. This is the fastest way to test a circuit but has the longest program development time. The technique is often used to prove the performance of the circuit and as a final confidence check on the circuit.

Types of fault detected:

• Fan-out
• Timing – fast / slow edges, propagation
• Faulty devices
• Short circuits, open circuits

Functional test cannot detect:

• Pull-up or Pull-down resistor missing
• Capacitors missing (eg decoupling)
• Passive component values

Diagnosys Products

The following Diagnosys products have functional test capability:

S500
S790 Series 2
PinPoint II-R