From Factory Floor to Cloud

Which industrial protocol is the vendor-neutral standard often used to read data from PLCs?

OPC UA

SNMP

SMTP

LDAP

or press Enter ⏎

That's right!

Right! OPC UA offers a secure, vendor-neutral information model that most modern PLCs and SCADA systems support.

Not quite!

It's OPC UA. It was designed for industrial automation, with typed data models and built-in security, unlike general IT protocols.

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In MQTT, what does a client connect to in order to publish and subscribe?

A topic server

A broker

A gateway hub

A message queue

or press Enter ⏎

That's right!

Yes! MQTT is publish/subscribe: clients never talk directly, a broker routes messages by topic.

Not quite!

The answer is a broker. Publishers and subscribers are decoupled, and the broker forwards each message to clients subscribed to its topic.

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A sensor reading must arrive exactly once, with no duplicates. Which MQTT QoS level guarantees this?

QoS 1 with retain

QoS 1

QoS 2

QoS 3

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That's right!

Correct! QoS 2 uses a four-step handshake to deliver exactly once, at the cost of more round trips.

Not quite!

It's QoS 2. QoS 0 is at most once, QoS 1 at least once (duplicates possible), and there is no QoS 3.

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Scratch the card to reveal a fact about MQTT.

MQTT was invented in 1999 to monitor oil pipelines over expensive, unreliable satellite links.

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How does a device usually authenticate to AWS IoT Core over MQTT?

Username and password

Shared API key

IP allow-list

X.509 client certificate

or press Enter ⏎

That's right!

Exactly! AWS IoT Core uses mutual TLS with X.509 certificates, and an attached IoT policy controls what the device may do.

Not quite!

The answer is an X.509 client certificate. Mutual TLS proves the device's identity, and IoT policies then authorise its topics and actions.

To get feedback you first need to answer the question above.

or press Enter ⏎

Old PLCs speak Modbus only. Where is the data typically translated to MQTT?

Inside AWS IoT Core

On an edge gateway

In the MQTT broker

In the cloud database

or press Enter ⏎

That's right!

Right! An edge gateway, such as one running AWS IoT Greengrass, polls Modbus devices and publishes MQTT to the cloud.

Not quite!

It's an edge gateway. AWS IoT Core only speaks MQTT, HTTPS and similar, so legacy protocols are translated on site first.

To get feedback you first need to answer the question above.

or press Enter ⏎

Flip the card to reveal a fact about PLCs.

The first PLC, the Modicon 084, was built in 1968 for General Motors to replace walls of relay wiring.

Did you know?

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Which AWS IoT Core feature routes incoming messages to services like S3, Lambda or Kinesis?

Rules engine

Device shadow

Fleet indexing

Job service

or press Enter ⏎

That's right!

Yes! The rules engine runs SQL-like queries on topics and sends matching messages to other AWS services.

Not quite!

It's the rules engine. You write a SQL-like statement on a topic filter and attach actions such as Kinesis, S3 or Lambda.

To get feedback you first need to answer the question above.

or press Enter ⏎

An app needs a machine's last reported state even while the machine is offline. What fits best?

A retained topic in S3

A Lambda cache layer

A Device Shadow

A Kinesis stream

or press Enter ⏎

That's right!

Correct! The Device Shadow is a JSON document with reported and desired state, readable even when the device is disconnected.

Not quite!

The answer is a Device Shadow. It stores the last reported and the desired state, and syncs with the device when it reconnects.

To get feedback you first need to answer the question above.

or press Enter ⏎

The factory's internet link drops for an hour. What prevents data loss at the edge?

Higher MQTT QoS in the cloud

A larger cloud broker

Shorter keep-alive timers

Store-and-forward buffering

or press Enter ⏎

That's right!

Right! Edge gateways buffer readings locally and forward them when the connection returns.

Not quite!

It's store-and-forward buffering. Nothing in the cloud can help while it's unreachable, so the edge must keep data until the link is back.

To get feedback you first need to answer the question above.

or press Enter ⏎

Drag the slider to reveal a fact about Modbus.

How old is Modbus?

Modbus dates from 1979 and is still one of the most widely used industrial protocols in factories today.

or press Enter ⏎

Orange industrial robot arms handle yellow crates in a large warehouse.

Why is a robot's emergency stop kept in the PLC rather than run from the cloud?

Cloud bills are too high

Latency must be deterministic

MQTT can't carry booleans

AWS forbids control use

or press Enter ⏎

That's right!

Exactly! Safety and control loops need guaranteed millisecond timing that a network round trip can't promise.

Not quite!

It's deterministic latency. Real-time control stays local; the cloud is for monitoring, analytics and slower decisions.

To get feedback you first need to answer the question above.

or press Enter ⏎

In the ISA-95 model, which level holds the sensors and actuators themselves?

Level 0

Level 2

Level 3

Level 4

or press Enter ⏎

That's right!

Correct! Level 0 is the physical process with sensors and actuators; PLCs sit at Level 1.

Not quite!

It's Level 0, the physical process. PLCs are Level 1, SCADA Level 2, MES Level 3 and ERP Level 4.

To get feedback you first need to answer the question above.

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Perfect! Every answer right!

10 of 10 right

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See your answers · all right

Question 1:
Which industrial protocol is the vendor-neutral standard often used to read data from PLCs?
OPC UA
SNMP
SMTP
LDAP
Right! OPC UA offers a secure, vendor-neutral information model that most modern PLCs and SCADA systems support.
It's OPC UA. It was designed for industrial automation, with typed data models and built-in security, unlike general IT protocols.
Question 2:
In MQTT, what does a client connect to in order to publish and subscribe?
A topic server
A broker
A gateway hub
A message queue
Yes! MQTT is publish/subscribe: clients never talk directly, a broker routes messages by topic.
The answer is a broker. Publishers and subscribers are decoupled, and the broker forwards each message to clients subscribed to its topic.
Question 3:
A sensor reading must arrive exactly once, with no duplicates. Which MQTT QoS level guarantees this?
QoS 1 with retain
QoS 1
QoS 2
QoS 3
Correct! QoS 2 uses a four-step handshake to deliver exactly once, at the cost of more round trips.
It's QoS 2. QoS 0 is at most once, QoS 1 at least once (duplicates possible), and there is no QoS 3.
Question 4:
How does a device usually authenticate to AWS IoT Core over MQTT?
Username and password
Shared API key
IP allow-list
X.509 client certificate
Exactly! AWS IoT Core uses mutual TLS with X.509 certificates, and an attached IoT policy controls what the device may do.
The answer is an X.509 client certificate. Mutual TLS proves the device's identity, and IoT policies then authorise its topics and actions.
Question 5:
Old PLCs speak Modbus only. Where is the data typically translated to MQTT?
Inside AWS IoT Core
On an edge gateway
In the MQTT broker
In the cloud database
Right! An edge gateway, such as one running AWS IoT Greengrass, polls Modbus devices and publishes MQTT to the cloud.
It's an edge gateway. AWS IoT Core only speaks MQTT, HTTPS and similar, so legacy protocols are translated on site first.
Question 6:
Which AWS IoT Core feature routes incoming messages to services like S3, Lambda or Kinesis?
Rules engine
Device shadow
Fleet indexing
Job service
Yes! The rules engine runs SQL-like queries on topics and sends matching messages to other AWS services.
It's the rules engine. You write a SQL-like statement on a topic filter and attach actions such as Kinesis, S3 or Lambda.
Question 7:
An app needs a machine's last reported state even while the machine is offline. What fits best?
A retained topic in S3
A Lambda cache layer
A Device Shadow
A Kinesis stream
Correct! The Device Shadow is a JSON document with reported and desired state, readable even when the device is disconnected.
The answer is a Device Shadow. It stores the last reported and the desired state, and syncs with the device when it reconnects.
Question 8:
The factory's internet link drops for an hour. What prevents data loss at the edge?
Higher MQTT QoS in the cloud
A larger cloud broker
Shorter keep-alive timers
Store-and-forward buffering
Right! Edge gateways buffer readings locally and forward them when the connection returns.
It's store-and-forward buffering. Nothing in the cloud can help while it's unreachable, so the edge must keep data until the link is back.
Question 9:
Why is a robot's emergency stop kept in the PLC rather than run from the cloud?
Cloud bills are too high
Latency must be deterministic
MQTT can't carry booleans
AWS forbids control use
Exactly! Safety and control loops need guaranteed millisecond timing that a network round trip can't promise.
It's deterministic latency. Real-time control stays local; the cloud is for monitoring, analytics and slower decisions.
Question 10:
In the ISA-95 model, which level holds the sensors and actuators themselves?
Level 0
Level 2
Level 3
Level 4
Correct! Level 0 is the physical process with sensors and actuators; PLCs sit at Level 1.
It's Level 0, the physical process. PLCs are Level 1, SCADA Level 2, MES Level 3 and ERP Level 4.

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