I-O Display Systems Basic I/O Product - Manual (Page 9)

The Basic I/O 1
1-4(Vol.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.