User`s guide

Appendix A - Logic Application Examples
Basic PLC Ladder Logic
Release E UMC800 Control Builder User’s Guide 225
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Basic PLC Ladder Logic
Example 1 - Basic PLC ladder logic
LS 1 LS 2
SOL 1
(NO
Contact)
(NO
Contact)
Coil
Equivalent Boolean Logic Expression
UMC 800 Logic
This is a basic series circuit. If Limit Switch 1(LS1)
is ON and Limit Switch 2 (LS2) is ON, Solenoid 1 is
turned ON. Note LS1 and LS2 are shown in their normal
state, wired as Normally Open. When LS1 and LS2 are
ON that is their “logic true” state, allowing “power flow”
through to the solenoid.
A = LS1
B = LS2
C = Output
A * B = C
AND Symbol
This uses a basic 2 Input AND block connected to a
single output.
4 Function blocks are used.
“120 VAC Power Rails”
A
B
C
AND