18
CM2115
Inputs
5.2. Active-Low Digital Inputs
The CM2115 has 5 active-low digital inputs that are used for module addressing
when the CM2115 hardware is configured as a VMM module:
INPUT17_D
to
INPUT21_D
5.2.1. Active-Low Digital Input Capabilities
The following table provides specifications for the CM2115 active-low digital
inputs:
Active-Low Digital Input Specifications
Item
Min
Nom
Max
Unit
Input voltage range
0
-
32
V
Over-voltage -
-
36
V
Pull-up resistance
9.8 k
-
10.2
k
Ω
Minimum negative going threshold
0.9
-
-
V
Maximum positive going threshold
-
-
2.15
V
Cutoff frequency (hardware)
-
80
-
Hz
De-bounce
time
1
-
-
-
ms
Wetting current
316
-
343
uA
Leakage current sleep mode - pin
grounded or floating
- 0 -
A
5.2.2. Active-Low Digital Input Installation Connections
An active-low digital input is typically connected to a switch that is either open or
closed.
When the switch is open, the pull-up resistor will ensure no signal exists on
the input pin, which will be interpreted by the CM2115 as inactive.
When the switch is closed, the input is connected to ground, which will be
interpreted by the CM2115 as active.
The active-low input must be connected to ground to ensure there is a ground
connection when the state of the input changes.
1
De-bounce time for address inputs is based on hardware cutoff frequency. The software reads the address in succession
during power-up until it receives two consecutive results that are the same. The time between readings is in the microsecond
range so there is technically no software de-bounce on these inputs.
