CPE Troubleshooting & Maintenance Techniques 4

Question 1

A repeater is used in a PROFIBUS DP network. Which statement about repeater placement is correct?

Accepted Answer

A repeater counts as one device on each of the two segments it connects

Answer

A PROFIBUS repeater occupies one device address on each segment it bridges, so each segment can have a maximum of 31 field devices plus the repeater (32 total).

Question 2

When replacing a PROFIBUS slave device in a live plant, which precaution is MOST important to ensure minimal disruption?

Accepted Answer

Ensure the replacement device has the same PROFIBUS address and GSD parameters as the original

Answer

The replacement device must have the identical PROFIBUS node address and compatible GSD configuration so the master can automatically re-establish communication.

Question 3

What diagnostic information is contained in the 'Manufacturer Specific Diagnostic' portion of a PROFIBUS slave's diagnostic response?

Accepted Answer

Device-specific fault codes, status information, and operational data defined by the device manufacturer

Answer

The manufacturer-specific diagnostic area allows vendors to include device-specific information such as sensor faults, calibration status, and internal error codes beyond the standard PROFIBUS diagnostic bytes.

Question 4

A PROFIBUS network exhibits intermittent errors that are correlated with operation of nearby variable frequency drives (VFDs). The MOST effective solution is:

Accepted Answer

Install ferrite cores on PROFIBUS cables and verify proper cable shielding and grounding

Answer

Ferrite cores attenuate high-frequency EMI from VFDs, and proper shielding/grounding prevents inductive and capacitive coupling of noise onto the bus.

Question 5

Which parameter in the PROFIBUS DP master configuration defines how long the master waits for a slave's response before declaring a communication error?

Accepted Answer

Tslot (slot time)

Answer

Tslot (slot time) defines the maximum time the master waits for a slave response token; if no response arrives within this window, a communication error is flagged.

(CPE) Certified Profibus Engineer Practice Test

(CPE) Certified Profibus Engineer Practice Test

CPE Troubleshooting & Maintenance Techniques 4