PLC I4 Flashcards
How does a discrete device work
On/off signal
How does analogue signal work
Variable range of signal
What category of device is discontinuous
Discrete
What category of device is continuous
Analogue
What is in a CPU
Power supply, memory, microprocessor
does the PLC power supply feed I/O
No. Only backplane, cards, processor
5 advantages of PLCs
Reliability Flexibility Expand ability Accuracy Ease of installation Maintain ability
What are the 2 types of PLC memory
Executive
User
How are IO modules addressed
According to their position in the rack
What are examples of discrete inputs
Switches or contacts that are either open or closed
What are examples of discrete outputs
Relays
Magnetic starters
Solenoid valves
Pilot lights
What always exists between field devices and the processor
Electrical isolation
What is most common way to switch power to the load
Triac
What is the purpose of a snubber and MOV
Limit peak voltage
Prevent electrical noise
What type of cable should be used for analogue devices
Shielded
What are the four basic functions of cards
Termination
Signal conditioning
Isolation
Indication
What is the purpose of a bridge rectifier on input module
Convert AC to DC
What is in a noise denounce filter of an input module
Capacitor and resistors
How does a capacitor reduce contact bounce
Provides a short delay when the switch closes
What is the purpose of a zener diode in an input module
To ensure the signal is at the rated level
How is voltage isolation achieved
An optical coupler
What does an optical coupler do
Convert input signal to 0-5v signal
What is a normal optical isolation ears no
1500 V RMS
What is the switch leg in a sinking module
DC positive line
