For The Profibus Expert - ABB PDP32.0 Manual

13 U N I V E R S A L M O T O R C O N T R O L L E R U M C 1 0 0 . 3
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For the PROFIBUS expert

The following section provides PROFIBUS know-how useful to better understand the PROFIBUS functions.
Cold start: The CheckCfg telegram sent from the PROFIBUS master defines the reference configuration. It is accepted if it is
error free. Otherwise, a negative reply with the appropriate diagnosis information is sent to the master. The PROFBUS
module arrives in the cyclical data exchange mode only if the reference configuration sent from the master corresponds with
the configuration sent from the connected device (i.e. UMC100).
Next, the PROFIBUS module waits for a parameter telegram from the bus master. Starting the cyclic PROFIBUS communi-
cation is only possible if a correct parameter telegram was received. The parameter telegram is sent to the connected
devices if parameter "Ignore block parameters" is not set to "Ignore".
Online reconfiguration: PROFIBUS module does not support 'Hot Configuration In Run' as supported by some ABB control
systems. Whenever a configuration change is done, the module must be restarted to ensure that the configuration gets
accepted.
Reaction on wrong configuration telegrams: The wrong configuration or parameter telegrams can occur if the used GSD file
does not belong to a device or the device version. In this case, the PROFIBUS module does not accept the configuration
telegram and leaves cyclic operation mode or does not start the PROFIBUS communication.
Online re-parameterization of devices: Because parameter changes do not affect the structure of the I/O data re-compi-
lation of the user application in the master is usually not necessary. In some control systems, a restart of the master must be
performed that makes online re-parameterization impossible. Other masters are not subject of this limitation and support
online parameterization. UMC100 is able to receive parameter telegrams every time without leaving the cyclic operation
mode.
• The PROFIBUS specification allows the online re-parameterization only if the device is not operated in V1 mode.
This means that no acyclic communication is allowed from the cyclic bus master (class one master). However, systems us-
ing a so-called class 2 master for sending V1 requests and supporting sending a new parameter telegram whilst online are
capable to do online re-parameterization. If a specific control system is able to carry out online re-parameterization should
be found in the documentation of this system.
• Sending new parameters during cyclic operation can be critical. If parameters are out of range or cannot be accepted from
the device for a specific reason a device might leave the cyclical operation mode and enter an error of fail-save mode.
Please consult the manual of the connected devices for more information.
Reaction on Wrong Parameter Telegrams: The PROFIBUS module does not check the parameters itself. This can only be
done from the connected devices. If a faulty parameter telegram was received (e. g. wrong length), the PDP32 leaves the
cyclical operation mode and waits for a new parameter telegram.
V1 Requests from a Class1 Master: Different master classes are distinguished in a PROFIBUS DP-V1 network. The so-called
C1 master mainly performs the cyclical data exchange with the slaves. A typical C1 master is a control system, such as a PLC
or DCS that exchanges cyclical process data with the slave. If the DPV1 function has been activated via the GSD file, also
acyclical connections between a C1master and a slave can also be established when the cyclical connection o is being estab-
lished. If a class 1 master uses V1 services, it is physically and logically the same bus node doing V0 and V1 communication.
Before acyclic messages can be used for the C1 master a device must have entered the cyclic operation mode. This means
that the PDP32 must be first configured and parameterized before acyclic requests from a class 1 master are possible. PDP32
supports V1 requests from a class 1 master. Please see "Online re-parameterization" for further details.
V1 Requests from a Class2 Master: A C2 master cannot perform cyclical data exchange with the slaves. It is logically a
different bus node than a C1 master. Examples for a typical C2 master are visualization systems, temporary installed
programming devices (Notebook / PC) or maintenance management tools. The C2 master uses exclusively acyclic connec-
tions for the communication with the slaves. V1 connections allow for cyclical data exchange with the slaves by means of
Read or Write services. Several C2 masters can be active in a DP-V1 network. The number of C2 connections, which are estab-
lished to a slave simultaneously, are determined by the slave. PDP32 supports up to 3 concurrent class 2 connections.