ProSoft Technology MVI56-PDPS - Manual (Page 59)

Reference MVI56-PDPS ♦ ControlLogix Platform
Profibus DP Slave Communication Module
ProSoft Technology, Inc. Page 59 of 88
April 22, 2008
ControlLogix Processor Not in Run
Whenever the module detects that the processor has gone out of the Run mode
(that is, Fault or PGM), backplane communications will halt between processor
and module but not on PROFIBUS network. When processor is returned to a
running state, the module will resume communication with the Processor.
5.2.3 PROFIBUS DP Architecture
The PROFIBUS DP network supports multiple master systems with several
slaves.
The following table shows the most important features of PROFIBUS DP:
Standard EIN 501 70
DIN 19245
Transmission Equipment
(Physical) EIA RS-485
IEC 1158-2 (through link or coupler)
Fiber Optic Cable (not available)
Transfer Procedure Half-duplex
Bus Topology Linear bus with active bus termination
Bus Cable Type Shielded twisted pair conductors
Connector 9-pin D-Sub
Number of nodes on the bus Max: 32 with no repeaters
Max: 125 with 3 repeaters in 4 segments
Bus Access
Two different bus access procedures handle the various communication
requirements for the PROFIBUS DP topology:
ƒ
Token Passing
ƒ Polling
Token Passing
Token passing ring is the basis for communication between the more complex,
active stations. All stations have the same rights in that a token is passed from
station to station in a logical ring. The token is passed to each station with a
maximum, definable token cycle time. A station is given transmission rights for
the duration of time that it has the token.
Master/Slave Polling
Master/Slave polling guarantees a cyclic, real-time based data exchange
between the station with transmission rights, active station and its subordinates,
passive stations. In this case, the master is able to pass data to the slave and/or
receive data. The services in layer 2 (field-bus data link in ISO-OSI reference
model) organize this communication.