Parker Vansco - Page 29

User Guide 19
Inputs
The following table provides specifications for the VMM2404 general purpose
inputs when used as DC-coupled frequency inputs:
DC-Coupled Frequency Input Specifications
Item
Min
Nom
Max
Unit
Input voltage range
0
-
32
V
Pull-up / down resistance
3.1 k
-
3.5 k
Ω
Input resistance – pull-up/pull-down disabled
81 k
-
-
Ω
Input capacitance
9
10
11
nF
Frequency range @ 0.25 Vp-p
1
-
10000
Hz
Accuracy
-
-
5
%
Resolution
0.1
-
-
Hz
Switching threshold voltage (software)
-
Program-
mable
-
V
Leakage current sleep mode
- pin @ 12 V
-
-
4.1
mA
3.1.4.2. DC-Coupled Frequency Input Configuration Options
DC-coupled frequency inputs have 4 programmable gain and attenuation factors,
as indicated in Table 3.
The pull-up or pull-down resistors for DC-coupled frequency inputs can be
enabled or disabled; however, both pull-up and pull-down cannot be enabled at
the same time. The pull-up and pull-down resistance is 3.3 kΩ.
3.1.4.3. DC-Coupled Frequency Input Connections
When connecting DC-coupled frequency inputs, be aware of system noise and
ground level shift.
System Noise
DC-coupled frequency inputs are more susceptible to system noise than digital
inputs.