Hardy HI 6500 Series - Manual (Page 55)

Network Configuration 47
•
•
•
•
•
•
Profibus-DP
The Profibus ® -DP (Decentralized Peripherals) communication profile is designed for
efficient field-level data exchange. Central automation devices, such as PLC/PC or process
control systems, communicate through a fast serial (RS-485) connection with distributed
field devices, e.g. PLCs. To begin communicating weighing parameters between an HI
6000 Series controller and a PLC, PC or DCS system controller, you need only to load the
*.GSD file and set the node address.
Wiring For Profibus, connect the two wires to pins 3 and 4.
Profibus Configuration
Profibus-DP operates using a cyclic transfer of data between master(s) and slave(s) on an
RS-485 network. An assigned master periodically requests (polls) each node (slave) on the
network. The HI 6500 or HI 6510 is a slave device. All data communication exchanges
between a master and the HI 6500 or 6510 originate from the master device. Each HI 6500
or HI 6510 is assigned to one master and only that master may write output data to that HI
6500 or HI 6510. Other masters may read information from any slave, but can only write
output data to their own assigned slaves.
Because Profibus uses a cyclic (periodic) polling mechanism between masters and slaves,
it is also deterministic. Therefore, behavior of a Profibus system can be reliably predicted
over time. Profibus is designed to guarantee a deterministic response.
The length (and timing) of the I/O data to be transferred from a single slave to a master is
predefined in the slave's device data base or GSD file. The GSD files of each device
connected via the network (slaves and class 1 masters only) are compiled into a master
parameter record which contains parameterization and configuration data, an address
allocation list, and the bus parameters for all connected stations. A master uses this
information to set up communication with each slave during startup. Slaves can only
acknowledge the messages they receive or transfer messages to a master when the latter
requests a slave to do so. Slaves are also designated as passive nodes.
Refer to the section, “I/O Tables For Communications to PLCs,” earlier in this chapter for
an understanding of the data and format for the Profibus communications.
For a full list of command parameters, please see the "Default Parameter IDs and Values"
at the end of Chapter 5.
NOTE Profibus-DP provides a very flexible network solution. In addition to the basic
guideline provided in this manual, your installation could require procedures that are
beyond the scope of this manual. For more information and to locate lists of links to
other sources of Profibus-DP information, check the Profibus website at
http://www.profibus.com .