Vishay G4, Technical Manual, Page: 142 / 200

Technical Manual
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Fieldbus interface
The optional fieldbus interface is based on a network communication module from
HMS Industrial Networks. Available fieldbusses are Profibus and DeviceNet. With
setup parameters the fieldbus interface is configured for the specific needs of an
installation. It is possible to setup address, baud rate (if applicable to the actual fieldbus
type) and mapping of the memory area in the fieldbus module that is available to the
network.
The mapping is divided in one base block for data from the master to the instrument,
one base block for data to the master from the instrument and 0 – 12 (selected with a
setup parameter) configurable data blocks. The base blocks are mandatory. The data
blocks are configurable regarding the content and in some cases also format (floating-
point or integer).
The registers mentioned below are Modbus registers as defined in section
Communication – Modbus Protocol. Each Modbus register is two bytes wide. This
section also describes commands.
The size of the base blocks is 16 bytes from master to instrument and 32 bytes from
the instrument to the master. The base blocks contain Instrument Error and Instrument
Status. Besides instrument error and status information are the base blocks used for
general purpose reading and writing of data and also for issuing commands to the
instrument.
The mapping in the master and the instrument must always correspond.
Setup of fieldbus communication
•
Complete the set-up of fieldbus communication before connecting it to the network
to avoid possible network failure due to mismatch in configuration between network
and instrument.
•
Select the fieldbus type used in the ‘Hardware Configuration’ menu. Note that the
instrument will be restarted after changes in the hardware setup.
•
Select the appropriate device address for the instrument. Address is setup in menu
‘Communication – Fieldbus’. Note that the address range is depending on type of
fieldbus.
•
Select baudrate, if applicable, according to the used baudrate in the network. Some
fieldbusses may support automatic baud rate setting. Use fixed baudrate setting if
there are difficulties to connect to the network or if the network baudrate is known.
•
Select the number of data blocks that is needed for the installation. It is possible to
use only the “base block” mapping if there is room for all necessary data within the
12 consecutive modbus registers that are defined within the base block (data from
the instrument). The starting address of the read area is settable.
•
Configure the desired number of data blocks. Note that the data blocks may still be
configured as ‘Not In Use’ in which case the data within the block will be undefined.
•
Check that the configuration of the master is compatible with the actual configuration
of the instrument.
•
Connect to the network.