CAS Automation Specialist Network Communications & Protocols Flashcards
7 cards from real CAS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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In PROFINET IO, what is the role of the IO Controller?
Answer: It runs the automation program and communicates with IO Devices
The IO Controller (typically a PLC) runs the user program and exchanges cyclic process data with IO Devices (field devices) over the PROFINET network.
Which feature of managed industrial Ethernet switches is critical for ensuring real-time performance in motion control applications?
Answer: IEEE 1588 Precision Time Protocol (PTP) support
IEEE 1588 PTP allows sub-microsecond clock synchronization across networked devices, which is essential for coordinated motion control applications.
What does the acronym 'CIP' stand for in the context of EtherNet/IP and DeviceNet?
Answer: Common Industrial Protocol
CIP (Common Industrial Protocol) is the application layer protocol shared by EtherNet/IP, DeviceNet, and ControlNet, providing a unified object model for automation devices.
In industrial networking, what is the primary advantage of using a ring topology with Media Redundancy Protocol (MRP)?
Answer: Automatic network recovery within milliseconds after a cable break
MRP enables ring networks to automatically reconfigure and restore communication in less than 200 ms (typically under 20 ms) after a single network fault.
Which function block in IEC 61131-3 is commonly used to send explicit Modbus TCP read requests from a PLC to a remote device?
Answer: MODBUS_CLIENT
The MODBUS_CLIENT function block (as defined in IEC 61131-3 and vendor implementations) handles explicit Modbus TCP requests, specifying function codes, register addresses, and data.
What is the maximum data rate supported by the FOUNDATION Fieldbus H1 physical layer?
Answer: 31.25 kbps
FOUNDATION Fieldbus H1 operates at 31.25 kbps over twisted-pair wiring and also supplies power to field devices over the same two wires.
When configuring VLANs on an industrial managed switch, what is the primary security benefit in an automation network?
Answer: Isolating control traffic from corporate IT or guest networks
VLANs logically separate network segments so that control traffic (PLC-to-I/O) is isolated from IT or other networks, reducing exposure to cyber threats and broadcast storms.