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Automating Manufacturing Systems - Process Control and ...

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plc wiring - 3.10<br />

24 V DC<br />

Output Card<br />

00<br />

01<br />

02<br />

03<br />

04<br />

Relay<br />

120 V AC<br />

Power<br />

Supply<br />

Neut.<br />

Motor<br />

05<br />

06<br />

24 V Lamp<br />

07<br />

COM<br />

in rack 01<br />

I/O group 2<br />

+24 V DC<br />

Power<br />

Supply<br />

COM<br />

O:012<br />

03<br />

Motor<br />

O:012<br />

07<br />

Lamp<br />

Figure 3.5<br />

An Example of a 24Vdc Output Card (Sinking)<br />

In this example the outputs are connected to a low current light bulb (lamp) <strong>and</strong> a<br />

relay coil. Consider the circuit through the lamp, starting at the 24Vdc supply. When the<br />

output 07 is on, current can flow in 07 to the COM, thus completing the circuit, <strong>and</strong> allowing<br />

the light to turn on. If the output is off the current cannot flow, <strong>and</strong> the light will not<br />

turn on. The output 03 for the relay is connected in a similar way. When the output 03 is<br />

on, current will flow through the relay coil to close the contacts <strong>and</strong> supply 120Vac to the<br />

motor. Ladder logic for the outputs is shown in the bottom right of the figure. The notation<br />

is for an Allen Bradley PLC-5. The value at the top left of the outputs, O:012, indicates<br />

that the card is an output card, in rack 01,inslot2 of the rack. To the bottom right of the<br />

outputs is the output number on the card 03 or 07. This card could have many different

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