How do I terminate PROFIBUS cables?
Termination Of Profibus Cables A Profibus termination is done by inserting a 220 Ω resistor in each end of the Profibus line. So, you insert a 220 Ω resistor in the first and one in the last station. The reason for using a 220 Ω resistor is that the two 220 Ω resistors are connected parallel to each other.
Where does PROFIBUS have to be terminated?
Therefore you must observe that PROFIBUS segments are only terminated at the two segment ends and nowhere else. Any additional terminations can cause corruption of the PROFIBUS signals and network malfunction.
What voltage is PROFIBUS DP?
Both the slave and master PROFIBUS DP test specifications state that the differential voltage between A- and B-lines shall be a minimum of 4 V and a maximum of 7 V. The signals of the A- and B-line are measured against DGND.
What is the difference between PROFIBUS DP and PA?
PROFIBUS PA is a variant of PROFIBUS DP that is specially designed for improvement and replacement of conventional systems such as 4-20 mA and HART in process automation. In contrast to PROFIBUS DP, data and power supply are transported over the same two wires and there is an explosion proof option available.
Why are termination resistors important in a PROFIBUS system?
PROFIBUS uses a differential path, which is designed to resist distortion due to external signals. However, termination resistor design is essential for the reflection effect cancellation. The termination resistance and the line-to-line impedance must match for the reflected wave attenuation.
How does PROFIBUS DP work?
ProfiBus DP normally operates using a cyclic transfer of data between master(s) and slave(s) on an RS485 network. That is, an assigned master periodically requests (polls) each node (slave) on the network. All data communication exchanges between a master and slave originate from the master device.
What is the difference between PROFIBUS and PROFIBUS DP?
What is DP in PLC?
DP stands for Decentralized Prepherals, and Profibus stands for Process Field Bus.
Why is the Profibus cable terminated at the end?
To minimize signal reflections the Profibus cable has to be terminated in the end. Signal reflection occurs when in a signal transmitted by a transmission media, such as copper cable or an optical fiber, some of the signal energy may be reflected back, instead of being passed all the way along the cable to the second end.
Do I need a connector for PROFIBUS station connection?
Unless using pre-made cable assemblies, the connector must be fitted to the PROFIBUS cable. The PROFIBUS cables are normally daisy-chained through the connector. This allows PROFIBUS station connection without using T-junctions (which introduce spur lines).
What is the VOD of PROFIBUS cable?
The equivalent differential termination is 171 Ω, and a typical PROFIBUS cable has a characteristic impedance of 150 Ω. This reflection adds to the already high VOD(PP)values, and in the nominal 5-Vcase, the VOD(PP)value increases to 6.65 V (6.24 × 1.07).
How to install PROFIBUS lightning and over-voltage protection system?
• Ground the auxiliary terminal box. • Integrate PROFIBUS cables routed outside of buildings in the lightning and over-voltage protection system. The planning of the lightning and over-voltage protection system should be done by a specialist company. Use an over voltage-protector between the standard bus cable and the direct-buried cable.