Input And Output Types Flashcards
(17 cards)
Range of AC and DC voltage operated
24/48/120/230
In DC input, what is the use of D1
It provides reverse polarity protection, the forward bias voltage will appear across the opto
In DC input, what is the use of D2 and R2?
D2:
LED used to give indication that an output is present
R2:
Limits current through D2
The states of digital input
Off: input voltage between zero and maximum threshold volts.
On: represented by a main threshold voltage and full voltage being applied
The use of optical isolation in DC input
Separates the line or input voltages from the logia circuits, it also prevents voltage transients from damaging the processor
Also helps reduce the effect of electrical noise
What happens to the AC input?
What does r do
The use of RI and C
AC input is rectified by the full wave bridge rectifier
R limits the current
R1 and C provides filtering
The opto-isolator in AC input
Provides galvanic isolation and isolates the internal logic from field wining voltage surges and short circuit
The two states of digital input
Off: represented by any input voltage between zero and maximum threshold volts
On: represented by min threshold voltage and full voltage applied
Optical isolation in DC input
Separates the line or input voltage from the logic circuits but also prevents voltage transients from damaging the processor
Also help reduce the effect of electrical noise
What happens to the AC input
The use of R
RI and C
AC input is rectified by the full ware bridge rectifier
R limits the current
R1 and C provides filtering
The use of opto-isolation in AC input
Provide galvanic isolation and isolates the internal logic from field wiring voltage surges and short circuits
Zenner diode in AC input
Sets a threshold. The output of the bridge needs to be the Zenner volts + Otto volts before Otto is then on
Explain AC/DC circuit
Two resistors set a threshold
Rand C provides high frequency filter
High Hz gives low xc short cct, voltage across CCT zero will appear across the opto
Relay output
Isolation of the internal electronics from external field wiring voltage spike and galvanic ISO ration is provided as there is no electrical link between them
Explain transistor and triac
DC output
The optocompler provides isolation, an output fuse will be required as the transistor isdamaged if overcurrent is allowed
Protection of output module switching devices.
Relay type outputs are prone to arcing
when switching off inductive loads such
as solenoids and contactors.
The diode connected across the load will
allow any inductive back emf to be
dissipated without damaging the relay.
How to save space when grouping many inputs in PLC with their own conditioning circuits
They are often grouped with only one common brought out to the terminal block
