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04_PLC_1_Digital Output.doc

Programmable Logic Controller

Handout

INDUSTRIAL AUTOMATION AND NETWORKING SECTION

EA5 - Programmable Logic Controller

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Function:

Receive signal from the CPU and converts them into forms that are appropriate to

produce control actions by external devices such as solenoids, motor starters.

Digital (on/off ) output signal:

There are several types of digital output module:

� Relay

� Triac

� Transistor

� Current sourcing

� Current sinking

� TTL

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04_PLC_1_Digital Output.doc

Programmable Logic Controller

Handout

INDUSTRIAL AUTOMATION AND NETWORKING SECTION

EA5 - Programmable Logic Controller

Output devices that receive on/off signal from the PLC:

� Indicator lights

� Motor starter coil/contactor

� Fluid power valve solenoids

� Siren/buzzer

There are LEDs indicating the status of the signal sent to each device connected to the

output channels. These LEDs are very useful in troubleshooting.

� Relay output card

Page 3

04_PLC_1_Digital Output.doc

Programmable Logic Controller

Handout

INDUSTRIAL AUTOMATION AND NETWORKING SECTION

EA5 - Programmable Logic Controller

� Triac output card

� Transistor output card