User`s guide

Appendix A - Logic Application Examples
Basic PLC Ladder Logic
Release E UMC800 Control Builder User’s Guide 227
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Example 4 - Basic PLC ladder logic
LS 1 LS 2
PB1
PumpB
PS1 PS2
SOL1
Pump A On
This expands the Example 3 to include more
permissive limit switch and pressure switch
contacts. In addition, a second output is activated
to turn on a panel lamp.
Equivalent Boolean Logic Expression
UMC 800 Logic
((A * B) + C)*D*E*F*G = Output
This uses a basic 2 Input AND block, a 2
Input OR block, and an 8 Input AND block.
UMC logic blocks allow any input to be
Negated, removing the need for Inverter
blocks. This is done for the Pump B input.
Note that Negated inputs (Logic NOT) are
specified for pins 6, 7 and 8 for unused
inputs (which are normally set to 0) to
make them “logic 1” so only the used pin
inputs 1 thru 5 affect the AND function).
Also, multiple DO outputs may be
connected to any logic block as shown.
12 Function blocks are used.
LS4
to this point
Boolean NOT symbol (negative logic)
(NC
Contact)