ABB NPBA-12, Installation And Startup Manual

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NPBA-12 Installation and Start-up Guide 2-1
Chapter 2 – Overview
Overview
This chapter contains a short description of the PROFIBUS standard
and the NPBA-12 Adapter Module, a delivery checklist, and warranty
information.
PROFIBUS PROFIBUS is an open serial communication standard that enables
data exchange between all kinds of automation components. There are
three main variations of PROFIBUS: PROFIBUS-FMS
(Fieldbus
Message Specification) , PROFIBUS-DP (Decentralised Periphery) and
PROFIBUS-PA (Process Automation) . The NPBA-12 PROFIBUS
Adapter Module supports the PROFIBUS-DP and PROFIBUS-DPV1
protocols.
The physical transmission medium of the bus is a twisted pair cable
(according to the RS-485 standard). The maximum length of the bus
cable is 100 to 1200 metres, depending on the selected transmission
rate (see Appendix C). Up to 31 stations can be connected to the same
PROFIBUS system without the use of repeaters. With repeaters, it is
possible to connect 127 stations (including the repeaters, and the
master station) to the system.
In PROFIBUS communication, the master station – usually a
programmable logic controller (PLC) – polls the slaves which respond
and take the actions requested by the master. It is also possible to send
a command to several slaves at the same time; in this case the slaves
send no response message to the master. Communication between
the slaves is not possible on a PROFIBUS link.
The PROFIBUS protocol family is specified in the EN 50170 Standard.
The communication with a drive is discussed in
PROFIDRIVE-
PROFILE – The PROFIBUS Profile for Adjustable Speed Drives. For
further information on PROFIBUS, refer to the above-mentioned
standards.