PC Control / Profi Control 645-12M Instruction Manual pdf - Kuhnke

PC Control 645-12M on PROFIBUS
4.9. PC Control 645-12M on PROFIBUS
PC Control 645-12M is a programmable logic controller
without any I/Os of its own. PROFIBUS is the medium via
which the controller communicates with the appropriate I/
O devices, i.e. the DP slaves. In this type of network, PC
Control 645-12M acts as a DP master (class 1).
The protocol used for communication between master and
slaves is called PROFIBUS-DP. This protocol supports data
transfer rates (baud rates) of up to 12 Mbit/s which all
network devices must be capable to sustain, however. If
there are slower devices in the network, the master is to
be set to the relevant baud rate by means of VEBES.
PC Control can maintain connections to up to 99 slaves
whose addresses are to be in the range from 0 to 99. A
process image memory provides the interface between
PROFIBUS (and, thus, the DP slaves connected to it) and
the master's user memory. VEBES, the network
configurator, divides the process image up, making the
individual memory locations available as "external
operands".
see chapter "4.5.2. External operands"
The following sections describe the extended functions for
the handling of DP slaves and data traffic via PROFIBUS.
Although they are not absolutely required for "normal"
operation they do help you take specific action to react to
special situations.
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