GE GFK-0804B Programming a Normally-Closed Contact in Series, Programming a Normally-Closed Contact in Parallel

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4-8 Micro PLC Programmer’s Guide – April 1994 GFK-0804B
Programming a Normally-Closed Contact in Series
When a Normally-Closed contact is not the first element of the rung, program an
AND NOT with the HHP, as shown below. The example shows how to use the HHP to
program a Normally-Closed contact at the first and second positions in a rung.
Ladder Diagram Hand-held Programmer
Timing Diagram
NAND operation of inputs I3 and
I4; output O18 is 1 when I3 and I4
are both 0.
I3 O18 START
AND
OUT
F3 (NOT)
F3 (NOT)
Output O18
I4 I3
I4
O18
Input I3
Input I4
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Programming a Normally-Closed Contact in Parallel
To enter a Normally-closed contact in parallel, as shown by I3 in the following example,
program an OR NOT with the HHP.
Ladder Diagram Hand-held Programmer
Timing Diagram
OR operation of inputs I1 and I2
and the reverse signal of I3. The
output O17 is 1 when either I1 or
I2 is 1 or I3 is 0.
I1 O17
I3
START
OR
OR
OUT F3 (NOT)
I1
I2
I3
O17
Input I1
Input I3
Output O17
I2
Input I2
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