User Guide
3
2.2 Port Specifications (Output Mode)
Output voltage (no load):
Output ON/HI, Nominal 5 V (Minimum 4.5 V)
Output OFF/LO, Nominal 0 V (Maximum 0.1 V)
Output sink current:
Output will sink 8.6 mA from a 5 V source
1
Output source current:
Output will source 42 mA @ 3 V, 133 mA short-
circuited to ground
1
Max. output current:
Limited by the 12 V supply.
(total for all outputs)
2.3 Port Specifications (Input Mode)
Input voltage:
Input high, 4.0 V minimum threshold
Input low, 1.0 V maximum threshold
All inputs feature Schmitt triggered detectors.
Input protection:
The input is clamped at -0.6 V and +5.6 V relative
to ground via a 33
resistor
1
. This will withstand
a continuous current flow of 200 mA (including
that which might be caused by accidentally
connecting directly to a 12 V supply). To limit
power dissipation and damage at higher voltages
than 12 V, an external series current limiting
resistor is recommended.
Input impedance:
The input is biased to +5 V relative to ground by a
100 kohm resistor.
2.4 Pulse Counting Specifications
Maximum frequency:
2.048 KHz on all channels simultaneously with
switch debounce-mode set off, with a 50/50 duty
cycle.
150 Hz on all channels with default switch
debounce timing enabled and a 50/50 duty cycle
2
.
Minimum frequency:
a frequency of 0 Hz is measured if there are less
than two high-to-low signal transitions in the
measurement interval.
Minimum pulse width:
a pulse must stay high or low for a minimum of
244
sec for a change of state or pulse to be
counted.
Switch debounce timing:
with the default settings a switch between the input
and G must remain closed for 3.17 msec and then
remain open for 3.17 msec, to be counted as a
closure2. The debounce time can be changed from
the user program.
