Defining The Bus Fault Reaction; Ignore Block Parameters; Change I/O Data Length On The Fieldbus - ABB UMC100.3 Manual

C O N F I G U R I N G T H E C O M M U N I C AT I O N I N T E R FA C E S

Defining the Bus Fault Reaction

Depending on the application the UMC is used in you might configure the reaction to a bus fault in a different way.
The bus fault reaction can be set the following way:
• Retain the present state (either running or stopped)
• Stop the motor immediately
• Start the motor in a forward direction (if actually in stop mode). If it is already running in a reverse or a
forward direction the motor keeps running.
• Start the motor in a reverse direction (if actually in stop mode). If it is already running in a reverse or a
forward direction the motor keeps running.
Relevant parameter:
• Bus Fault Reaction

Ignore Block Parameters

Block parameters can be used to parameterise a device from within the PROFIBUS master using the GSD file.
The PROFIBUS master then sends the parameters in one block (this where the name came from) to the device.
The block parameters are sent under certain conditions:
• Bus master start-up
• Device start-up
• During normal operation in case of parameter changes
If the UMC shall be parameterized via LCD panel or using the PBDTM the block parameters should not be sent.
As it is not possible to prevent the bus master from sending the block parameters the PROFIBUS communication interfaces can be
configured to stop forwarding these parameters to the UMC (i.e. ignore them).
To do so set parameter "Ignore Block Parameter" to "Ignore".
A typical customer error message if this parameter was not set is as follows: "We set up everything correctly and the
plant worked for weeks without problems. But then suddenly the UMC lost its parameters."
What happened: The UMC was configured e.g. via LCD panel during commissioning. Then weeks later the bus master
or controller was restarted for whatever reason and therefore sent the default UMC block parameters as they were
never set.
If you are unsure if the parameter was set correctly you can also lock the parameters in the UMC. Then no parameter
changes are possible anymore until the lock is reset. If locked the small "lock" icon
Relevant parameter:
• Ignore Block Parameters

Change I/O data length on the fieldbus

For some process control systems the I/O data size is limited, e. g. to 255 bytes for all slaves.
As a consequence only a small number of UMCs can be connected to such a fieldbus master.
In a situation like this, the I/O data size can be reduced to a lower value which allows to connect more UMCs to the network. The
UMC simply cuts the data length as shown in section "Parameters and Data Structures on a Fieldbus".
For the short profile (Profile2) no PROFIBUS DTM is available.
Relevant parameter:
• I/O Data Profile
appears in the LCD display.
97