15
Specifications for All Function Blocks Section 3-2
Setting: Dual Channel
Complementary (2 Pairs)
Discrepancy Time If the function block input type is set to Dual Channel, the discrepancy time
(i.e., the time between changes in the inputs) can be evaluated.
The time between when one of the dual-channel inputs changes until the
other one changes is monitored. If the second dual-channel input does not
change before the discrepancy time expires, an error will occur and the Out-
put Enable output from the function block will not turn ON.
The dual channel modes can be used to detect faults in safety devices and
safety device wiring monitored by the function block.
The discrepancy time monitoring time can be set to from 0 (disabled) to
30,000 ms in 10-ms increments. The discrepancy time setting is disabled if
Single Channel Mode is set.
The discrepancy time is evaluated when the input signal changes.
Input 1 (NC) Input 2 (NO) Input 3 (NC) Input 4 (NO) Output Enable
00000
00010
00100
00110
01000
01010
01100
01110
10000
10010
10101
10110
11000
11010
11100
11110
Dual channel mode Input signals Input signal status
Input 1 Input 2
Dual Channel Equivalent
• Input 1: NC
• Input 2: NC
00 Inactive
0 1 Discrepancy
1 0 Discrepancy
11 Active
Dual Channel Complementary
• Input 1: NC
• Input 2: NO
0 0 Discrepancy
01 Inactive
10 Active
1 1 Discrepancy
Parameters Setting range Default
Discrepancy time 0 to 30 s in units of 10 ms
Discrepancy time checks
are not performed when
this parameter is set to 0.
30 ms
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