Alldaq ADQ-51, Руководство пользователя

Страница: 12 / 24

12 Function groups
Function groups Manual ADQ-51 Rev. 1.0
3.3 Isolated digital inputs
The ADQ-51 has 1 isolated digital input port with 8 bits. The isolated inputs have a Schmitt
trigger characteristic according to IEC 61131-2 (Type 1) and are designed for a maximum input
voltage of 35 V. The ADQ-51 has 1 isolated digital input port with 8 bits. All isolated inputs are
equipped with status LEDs (not visible in the housing). The insulation voltage against PC ground
is 500 VACeff according to EN60664-1 or UL1577.
3.3.1 Digital input filter
You can program a digital filter for each input port to prevent unwanted contact bounce effects.
Choose between the following values:
10 ms (N = 1248) / 3.2 ms (N = 400) / 1.0 ms (N = 125) / 10 µs (Bypass). The scan frequency is
100 kHz (typ.).
0
1
2
N-1
N-2
N-3
Scan frequency
Input DI_x
Filter outlet
Filter status
Signal is 1
Signal is 0
Filter time
Signal is
unchanged
Fig. 3: Digital input filter
3.3.2 Wiring
The isolated inputs have a Schmitt trigger characteristic in accordance with IEC 61131-2 (type 1)
and are designed for the UIH input high level of typ. 24 V, which is common in control techno-
logy. Observe the following conditions:
• Threshold voltage L ¨ H: > 15 V @ UEXT = 24 V
• Threshold voltage H ¨ L: < 11 V @ UEXT = 24 V
• Hysteresis: typ. 1 V
The external supply UEXT can be in the range 16..35 V, while we recommend 24 V. Please note
that a ground connection must always be established from the external circuit to the reference
ground of the isolated digital inputs (GND). The digital input part and the digital output part
use a common GND.