| 摘要 |
PURPOSE: Apparatus for testing a transfer state of signal is provided to inspect semiconductor equipment efficiently by confirming simply the input/output for the signal to make use of the RS-485 or RS-422 communication standard. CONSTITUTION: The transmitting signal(TD+, TD-) and the receiving signal(RD+, RD-) of RS-485 or RS-422 communication standard is inputted in an input terminal(30) and output to an output terminal(32). A signal counter(34) between the input terminal(30) and the output terminal(32) samples the transmitting signal(TD+, TD-) and the receiving signal(RD+, RD-) to apply to a signal level controlling unit(36). The signal level controlling unit(36) applies the sampled signal to a light emitting unit(38), and controls the light intensity of light emission diodes(LED1¯LED4) in response to the state of the transmitting signal(TD+, TD-) and the receiving signal(RD+, RD-).
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