Installation & Commissioning Procedures Flashcards
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Read the first 7 Installation & Commissioning Procedures flashcards as text
What is the maximum allowed voltage drop across a PROFIBUS DP segment cable at full load?
Answer: 3.0 V
The allowed voltage drop across a PROFIBUS DP segment cable must not exceed 3.0 V to ensure reliable communication.
Which tool is commonly used during PROFIBUS commissioning to verify signal quality without disrupting live traffic?
Answer: PROFIBUS tester/analyzer
A PROFIBUS tester or analyzer can capture and decode bus traffic non-intrusively, allowing signal quality assessment during live operation.
When installing PROFIBUS cable in a cable tray alongside power cables, what is the minimum recommended separation distance?
Answer: 20 cm
A minimum separation of 20 cm between PROFIBUS cables and power cables is recommended to reduce electromagnetic interference.
What happens if a PROFIBUS DP slave device is powered on while the master is already in Data_Exchange mode?
Answer: The slave remains in Wait_Prm state until the master re-initializes it
A newly powered slave waits in Wait_Prm state until the master sends parameterization and configuration telegrams to initialize it.
Which PROFIBUS DP diagnostic flag indicates that a slave requires new parameterization data?
Answer: Prm_Req
The Prm_Req (parameterization request) flag in the slave diagnostic byte signals that the slave needs fresh parameterization from the master.
During segment commissioning, the bus monitor shows many CRC errors concentrated at one time of day. What is the most likely cause?
Answer: Cyclic electromagnetic interference from nearby machinery
Time-correlated CRC errors often indicate periodic EMI sources such as motors, drives, or welding equipment that operate on a schedule.
What is the purpose of the PE (Protective Earth) connection on PROFIBUS cable shielding?
Answer: To create a low-impedance path for noise currents away from signal conductors
Connecting the cable shield to PE provides a low-impedance return path for induced noise currents, preventing them from corrupting signal conductors.