Eaton Electrical D77A user manual Function, Discrete Input Module Operation

Intelligent Technologies (IT.) D77A I/O Module Products

I/O Function

Discrete Input Modules

Figure 17 illustrates the basic signal processing operation. When a signal is present at the input point, the module responds with the following sequence:

1.Optical Isolation — Optical isolation protects the I/O circuits and communication circuits from possible damage due to transients and over-voltage.

2.Debounce Logic/Control — A debounce circuit and software limits the effects of transients and electrical noise by requiring the input to be true for a certain period of time before the logic acknowledges a true signal. Once a true signal is achieved, the logic turns on the LED.

3.QCPort Com./Logic — The logic updates the QCPort communication on a regular, scheduled basis as to the status of the input point.

Inp ut	Optical	Debounce	QCPort
	Isolation	Logic/Control	Com.
	LED
	Indication
			D77A-004

Figure 17: Discrete Input Module Operation

Discrete Output Modules

Figure 18 illustrates the basic logic processing operation. When the processor activates an output point, the module responds with the following sequence:

1.QCPort Com./Logic — QCPort communication updates the logic circuit on a regular, scheduled basis as to the status of the output points.

2.Optical Isolation — Optical isolation protects the I/O circuits and communication circuits from possible damage due to transients and over-voltage. Once an active signal is transmitted to the optical isolation circuit, the LED is forward-biased.

3.Output Drivers — The driver activates the output point.

QCPort	Optical	Output	Output
Com.	Isolation	Dri vers
		LED
		Indication
			D77A-005

Figure 18: Discrete Output Module Operation

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