Download FM 352-5 High Speed Boolean Processor

Configuring the FM 352-5
5.7
Selecting Input Filters
Description of Filter Behavior
The filters in the FM 352-5 module are noise filters. Noise bursts are filtered out of
the input signal if the noise burst is less than the delay time. Pulses that are equal
to the delay time or longer will be passed through to your program. The filters delay
the input signal for the delay time.
The input delay for a given input will be determined by the input type, the voltage
swing of the signals, the time an input is held active or inactive and the delay filter
selected.
24 V Input Characteristics
The 24-V inputs are a slower input type and have the most variation due to the
input signal characteristics. The 24-V inputs have an asymetrical response to the
input voltage—the input is faster for turning on than turning off, and a saturation
effect—the longer an input is on, the longer it takes to turn off.
• Turn-on time is faster than turn-off time (turn-on time is typically 1.4 µs faster
than turn-off time).
• Turn-on time is faster with a higher voltage input (a 20-V input level is typically
0.25 µs slower than a 30-V input level).
• Turn-off time is faster with a lower voltage input (a 20-V input level is typically
0.6 µs faster than a 30-V input level).
• Turn-off time is slower when the input on-time is longer; inputs that are on for
0.5 µs typically turn off 1.4 µs faster than inputs that are on for 6 µs. (The
turn-off time does not increase for on-times greater than 6 µs.)
Table 5-3 gives the typical ON/OFF delays for each delay filter.
Table 5-3
Typical Delays for 24-V Discrete Inputs
On-Time Delay
Off-Time Delay
0
1.1 µs
2.5 µs
±0.04 µs
5
3.4 µs
4.8 µs
±0.09 µs
10
8.2 µs
9.7 µs
±0.25 µs
15
13.0 µs
14.5 µs
±0.4 µs
20
17.9 µs
19.3 µs
±0.6 µs
50
46.9 µs
48.3 µs
±1.6 µs
1600
1546 µs
1547 µs
±25 µs
Delay Filter
FM 352-5 High-Speed Boolean Processor
A5E00131318-03
Filter Variation
5-15