Rockwell Automation Publication 1794-IN102D-EN-P - July 2018
15
FLEX I/O AC Digital Input Modules
Setting the Input Filter Time
You can increase the input filter time (FT) for channels 00...07 (1794-IA8 and
1794-IA8I) and channels 00...15 (1794-IA16) by setting the corresponding bits
in the output image table (complementary word) for the module.
For example, to increase the off-to-on filter time to 12 ms for all inputs at address
rack 1, module group 0, set bits, and program as shown below.
To increase the filter time, set the bits according to the
Input Filter Time
table.
Image Table Memory Map for the 1794-IA16 Module
Dec
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Oct
17
16
15
14
13
12
11
10
7
6
5
4
3
2
1
0
Read 1
I15
I14
I13
I12
I11
I10
I9
I8
I7
I6
I5
I4
I3
I2
I1
I0
Write 3
Not used – set to 0
Input Filter FT
12...15
Input Filter FT
0...11
Where
I = Input
FT = Input filter time
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FT = 12-15
FT = 0-11
1794-IA8, 1794-IA8I
1794-IA16
O:010
Dec.
1
0
0
7
6
5
4
3
FLL
I:000
00
Fill File
Source
Destination
Length
#O:010
1
Write FT to complement
of input module.
Write filter time on system startup.
7
6
5
4
3
2
1
0
0
1
0
= 4 Octal or 4 Decimal
2
1
0
= 44 Octal or 36 Decimal
0
1
0
1
0
0
1794-IA8
1794-IA16
1794-IA8I