Automating Manufacturing Systems - Process Control and ...

plc wiring - 3.12
put card directly. When an output is on power will be supplied to that output. For example,
if output 07 is on then the supply voltage will be output to the lamp. Current will flow
through the lamp and back to the common on the power supply. The operation is very similar
for the relay switching the motor. Notice that the ladder logic (shown in the bottom
right of the figure) is identical to that in Figure 3.5. With this type of output card only one
power supply can be used.
We can also use relay outputs to switch the outputs. The example shown in Figure
3.5 and Figure 3.6 is repeated yet again in Figure 3.7 for relay output.
120 V AC/DC
Output Card
00
01
02
03
04
05
06
07 24 V lamp
in rack 01
I/O group 2
24 V DC
Power
Supply
Relay
120 V AC
Power
Supply
Motor
O:012
O:012
03
07
Motor
Lamp
Figure 3.7
An Example of a Relay Output Card