Profibus

PROFIBUS (Process Fieldbus)

                 It is a standard for fieldbus communication in automation technology. It is first given by German, used by Siemens. PROFIBUS is an open, vendor-independent protocol that became part of the international standard IEC 61158 in 2000. It has been classified into  two types,

1. PROFIBUS Decentralized peripherals (DP)

2. PROFIBUS Process Automation (PA) - Used in hazardous location

* Profibus used on ethernet known as PROFINET. Profinet is similar to industrial ethernet but it is different from Profibus.

                 The main fact among these classification is that, these Profibus DP and PA works on same protocol but the transmission media is different hence it is classified into two types.

• Profibus PA

                 It uses MBP-IS medium for transmission of signals at a single baud rate of 31.25 Kbps.  MBP-IS can also be used in potentially explosive environments.

• Profibus DP

                 It uses RS-485 copper, fiber optics, infrared and other media.

                 Network speed is shown as 9.6kbit/s (lower limit) to 12,000kbit/s (upper limit). Network speed may vary depending on the medium or technology used. Same protocol and the devices can exchange cyclic I/O data with a standard DP master.

Profibus network

What is MBP-IS ?

MBP (Manchester bus powered) transmission technology according to IEC 61158-2 type 1 is used with PROFIBUS-PA. This is the same procedure that is also used with other field buses, such as the Foundation Fieldbus (FF). Despite this, PROFIBUS PA and FF devices cannot be used on the same cable. With MBP, like RS 485, two-core, screened cable is used. However, there are significant differences in the installation technology.

•MBP works with current signals on the bus

•MBP works with a fixed bit rate of 31.25 kbit/s

•MBP can transmit data and supply for field devices on two wires

•MBP-IS can also be used in potentially explosive environments (EEx ia/ib IIC).

MBP segments are created with DP/PA couplers or link modules. Each MBP segment can connect up to 32 stations with a distance of up to 1.9 km. With MBP-IS explosion-save installations, however, these values are greatly reduced.