High-Speed Input and
Pulse Output Features
3–52
High-speed Input and Pulse Output Features
Mode 60: Discrete Inputs with Filter
The last mode we will discuss for the HSIO circuit is Mode 60, Discrete Inputs with
Filter. The purpose of this mode is to allow the input circuit to reject narrow pulses
and accept wide ones, as viewed from the ladder program. This is useful in
especially noisy environments or other applications where pulse width is important.
In all other modes in this chapter, X0 to X2 usually support the mode functions as
special inputs. Only spare inputs operate as filtered inputs by default. Now in Mode
60, all three inputs X0 through X2 function only as discrete filtered inputs.
Refer to the block diagram below. When the lower byte of HSIO Mode register V7633
contains a BCD “60”, the input filter in the HSIO circuit is enabled. Each input X0
through X2 has its own filter time constant. The filter circuit assigns the outputs of the
filters as logical references X0 through X2.
Output Circuit
Input Circuit
CPU
PLC
DL05
X0
Y0, Y1
X3- X7
Y2 - Y5
VĆmemory
V7633
0060
Mode Select
I/O data
HSIO
FILTERS
X0-X2
X1 X2
Signal pulses at inputs X0 – X2 are filtered by using a delay time. In the figure below,
the input pulse on the top line is longer than the filter time. The resultant logical input
to ladder is phase-shifted (delayed) by the filter time on both rising and falling edges.
In the bottom waveforms, the physical input pulse width is smaller than the filter time.
In this case, the logical input to the ladder program remains in the OFF state (input
pulse was filtered out).
Time
Physical Input X0
Filter Time
Logical Input X0
Physical Input X0
Logical Input X0
Filter Time
Purpose
Functional Block
Diagram
Input Filter
Timing Parameters
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