Table of Contents
Advertisement
915U-2 Wireless I/O
2.5.4 Pulsed Inputs
The 915U-2 supports 8 x digital signals, of which inputs 1-4 can be used as pulsed
inputs.
The maximum pulse frequency is 50 KHz for Input 1 & 2 and 1 KHz for Input 3 & 4.
Digital/Pulsed inputs are suitable for TTL signal Level, NPN-transistor switch devices or
voltage-free contacts (relay/switch with debounce capacitor).
TTL CMOS
Output
Transistor
Switch Device
Voltage Free
Frequencies greater than 1 KHz need to use a TTL logic drive or an external pull-up
resistor. Pulsed inputs are converted to two different values internally. First is the Pulse
Count, which is an indication of how many times the input has changed state over a
configured time period. Secondly there is a Pulse Rate which is an analog input derived
from the pulse frequency. E.g. 0 Hz = 4mA and 1 KHz = 20mA.
Page 29
Pulsed Inputs
Contact
Figure 14 – Pulsed Input Wiring
915U-2
V+
DIO1
DIO2
DIO3
Common
V-
Page 29
915U-2 Wireless I/O
Advertisement
Table of Contents
