I-O Display Systems Basic I/O Product manual Digital Inputs

The Basic I/O 1

DIGITAL INPUTS:

Digital input modules detect the presence or absence of a field signal. Module types vary from AC to dry contact sense. Because the industry standard modules are optically isolated, the response time performance of digital input instructions can be limited by the delay in the input modules themselves. Some modules can have rise and fall times of up to 40 milliseconds.

Digital input instruction types are:
Read	Read the On or Off state of all inputs. This data is
	updated every 10 Milliseconds.
Edge Detection	Off-to- On and On-to-Off transitions can be detected
	within 1 millisecond of their occurrence. Action is
	only reported every 10 milliseconds.
Pulse Widths	BASIC I/Os can report pulse width measurements
	from .01 seconds to 46.6 hours. Minimum resolution
	is .01 seconds (Pulse widths up to 10.9 minutes).
	Either on or off pulses can be measured.
Pulse Counting	Pulses can be counted up to a total of 65,535. To be
	reliably counted, pulses must have a minimum On and
	Off time of 1 millisecond. Thus the maximum
	counting rate for a 50% duty cycle square wave is
	once every 2 milliseconds (500Hz).
Frequency	Direct frequency measurements can be made on
	digital inputs at rates of up to 500 Hz with a user
	specified time base of from .01 to 2.55 seconds.

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