Deck 40: Analog Sensing for Programmable Logic Controllers

Question 1

It is common to find different pieces of equipment have ground levels that are several volts apart.

Answer 1

True

Question 2

What is the brute-force method?

Answer 2

When different pieces of equipment have ground levels that are several volts apart, large cable is sometimes used to tie the two pieces of equipment together. This forces them to exist at the same potential. This method is sometimes referred to as brute-force method.

Question 3

It is desirable for the sensor to produce a certain amount of ____________________ instead of a certain amount of voltage because it eliminates the problem of voltage drop on lines.

Answer 3

current

Question 4

What happens if the pressure sensor is located some distance away from the programmable controller?

Question 5

Most analog sensors can produce only very weak signals.

Question 6

Why should wire run as short as possible?

Question 7

Signal wire should run in the same conduit with power wiring.

Question 8

When it is necessary to cross power wiring, install the signal cable so that it crosses at a right angle.

Question 9

What does the differential amplifier detect?

Question 10

An electronic device that is often used to help overcome the problem of induced noise is the ____________________.

Question 11

Why should a common coaxial cable be avoided?

Question 12

A twisted pair of signal wires surrounded by a braided shield cannot be used as a type of signal cable.

Question 13

Because the sense resistor in the input of the programmable controller is the only resistance in the circuit, all of the ____________________ of the pressure sensor will appear across it.

Question 14

One of the most common types of shielded cable uses twisted wires with a(n) ____________________ foil shield.

Question 15

In an industrial environment where intense magnetic fields and large voltage spikes abound, it is easy to lose the ____________________ in the electrical noise.