data transmission, opened the door for industrial networks. Industrial networking
technologies offered the industry standard method of connecting devices together
for the transfer of data back to a controller and allowed for more flexible applications
and system expansion. Industrial networks use a high-speed communication
backbone that integrates Logic Controllers, PCs or workstations with devices in
the field to give the operator a user-friendly interface for communication with
each device location in the field. In case of Profibus, the devices are connected
with DCS through twisted pair Profibus special cable in “Daisy Chain” configuration.
Open communication networks permit any supplier to offer communications
facilities that can be readily linked to many other devices. In turn, the end user is
not handcuffed into buying equipment from propriety devices suppliers allowing
the user to gain benefits from the very latest and best technologies while still
remaining free to choose equipment from the open market.
The advantages of open networks are:
- Reduced hardwiring and less labor intensive construction of control panels
and systems - Reduced commissioning time as the set-up of these units is more akin to “Plug
and Play” - Reduced down time because improved status information can indicate degradation
of a driven unit - Faster replacement and re-commissioning of the systems
- Increased status information at minimal additional expense
- Simple interfacing to DCS systems
11.4 Present System in Cement Plant:
In existing new plants VFD, Weigh feeders, Bin Weighers, Belt Weighers /Pan
weigher, Rotoscale and other sub control system with Profibus connectivity as
well as hard wired. Reason behind the existence of both types of interfacing are
the non-availability of required signal information for control/monitor on Profibus,
especially in case of Weighing System Control panels and Variable Frequency
drives. Signals on Profibus are only used for monitoring purpose and control of
panel are through hardwire only.
11.5 Cost Comparison:
Following a case of VFD is taken, considering availability of complete information
on Profibus