Profibus
A Dynamic Force in Industrial Automationand Controls
Power Cordsets Pages 108-111 Molded Cordsets see Brad Harrison
® Designer’s Guide Network Interface see Industrial Communication
Solution Guide Power Media Gateways Power is supplied to the active modules via a 5 pole Mini-Change Seamlessly transfers data in real time between dissimilar network protocols. Double-Ended Cordsets Pages 88-89 Data Media The main Profibus cable is of a shielded twisted pair design. It does not con-
tain any conductors to power the Profibus modules or nodes, this is provid-
ed through the power media. The connectivity for the active modules uses a
shielded Brad Harrison reverse keyway, 5-pole connector design. The data
connectivity is complemented with T-Splitters to connect the bus to the
active modules and 9-pin D-sub connectivity for other Profibus compatible
devices. Media
COMPONENTS AND ELEMENTS OF PROFIBUS SYSTEM
Network Interface Profibus uses a linear bus topology. At lower speeds it can be used with
short drops from the main line to the active modules. Modules or nodes
connected to the bus in this way can be ‘hot swapped’ without taking the
bus off line. Unlike DeviceNet, the module or node power is not included
in the bus media and has to be provided by separate connections. The scanner resides in the host controller whether it is a PLC or PC, providing a network connection. The scanner exchanges a data table,
which is loaded with the various values of the inputs and outputs, with the
logic controller to solve the various logical expressions. Simultaneously, the
operation of the master and/or slave protocols is completed. The logical expressions are then re-exchanged with the data table for communication out to the various nodes and I/O residing on the network.
The scanner generally supports all standard baud rates of the network. Control Engine PC “soft controllers” or
Industrial plcs can act as the main logic solvers, taking the
current I/O status information of the network and solving these operations
through the main control program. The new status of the I/O is then
updated via the network interface to the actuators, starters and interface
panels. Many times a central control engine often acts as the Profibus
“master” which initiates and controls many of the messaging sequences
of the network.
® connector.Two of the contacts are used to provide power to the module’s electronic cir-
cuits and any input devices such as
proximity switches. A separate and isolated
power circuit is provided via another two contacts. This is used for output
devices only and is not required on input only modules. This second supply
should be controlled via the machine’s
safety systems to ensure that no outputs
are activated during
operator interface with the machine.
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