Using the IntelliLogger™
49
Additional Features:
The Digital Input channels on the ILIM-2 have additional features to simplify interface to
various types of digital input signals:
P
ULL
-
UP
(W
ETTING
)
VOLTAGE
:
For non-powered switch inputs (eg a reed switch or open-collector transistor) a
nominal 3.3V pull-up voltage (commonly referred to as a “contact wetting voltage”) is
supplied at each Input Channel via an internal 51kohm resistor to the 3.3Vdc internal
supply. This voltage eliminates the need for users to connect an external power
source in order to sense the open or closed state of the switch. When the switch is
open, the input will be 3.3Vdc (High) and when closed, 0Vdc (Low).
O
VER
-D
RIVING
E
VENT
I
NPUTS
:
As the Pull-Up voltage is provided via a 51kohm internal resistor, over-driving it from a
powered input (eg a PLC output that swings between 24Vdc and 0Vdc) is readily
done without harm to the input channel. Do not exceed 30Vdc input.
D
EBOUNCE OPTION
:
Contact bounce is a phenomenon that can occur when a mechanical switch closes.
During switching, the physical electrical contacts inside the switch can bounce against
each other a number of times opening and closing the circuit before they settle to their
final state. As the counter input circuitry in the logger is extremely fast, these bounces
may be counted as transitions (in count mode), resulting in technically accurate but
undesired data.
To help correct for this problem, a 40mS hardware debounce circuit is built into each
channel. By enabling the debounce function, typical short duration contact bounce will
be filtered out. Activate Hardware Debounce if you suspect false transitions due to
switch bouncing.
3-22; Simplified Event/Counter Input Channel Schematic
E
VENT
/C
OUNT
/O
UTPUT
C
HANNELS
(C
HANNELS
I – P)
The ILIM-2 has 8 additional channels that can be configured by the user as either Event, high-
speed Counter inputs or as Open Collector Outputs. These channels are identical to
Event/Counter channels A to H (see above) except that they alternatively can be configured
as Outputs on a channel by channel basis. Users configure each Channel using HyperWare,
