User manual

Chapter 4 Configuration
Page 79 ©February 2009
4.9.1 Fieldbus Mappings
The Fieldbus Interface is divided into two distinct areas. The IN Area contains input data that is
made available to the host device. The OUT Area contains output data from the host device. This
is in contrast to the Radio Interface, in which each 16-bit register can be used as input or output.
Also note the size of the Fieldbus Interface is variable, depending on the type of fieldbus.
E-Series Configuration Software provides user configurable Fieldbus Mappings to link the
required Fieldbus I/O to the Radio Interface. Write mappings write I/O values from the Radio
Interface to the Fieldbus IN Area. Read mappings read I/O values from the Fieldbus OUT Area
to the Radio Interface.
If you want to send a value from the 105G to the host device, use a Fieldbus Write Mapping. The
input data from the Radio Interface (i.e. input data that has either come in from the radio or from
local I/O) will be transferred to the IN Area via the fieldbus write mapping. The host device can
then read this input data from the IN Area.
If you want to send a value from the host device to the 105G, use a Fieldbus Read Mapping. The
host device can write output data to the OUT Area. The output data from the OUT Area will then
be transferred to the Radio Interface via the fieldbus read mapping. The radio driver can then
either send this output over the radio or to a local I/O.
Several different configurable transfer modes are also available for fieldbus mappings to ensure
the I/O is formatted according to the requirements of the particular fieldbus protocol or host
device. The six possible types of Fieldbus Mapping are outlined in the table below.
Fieldbus Mapping Types
Transfer
Mode
Read Mapping Write Mapping
Single Bit
The 105G reads a block of
consecutive bits from Fieldbus
OUT Area and stores each bit in
consecutive I/O Registers, as hex
FFFF or 0000.
The 105G takes the MSB (most
significant bit) of a block of consecutive
I/O Registers, converting the 16 bit I/O
register values into 0 or 1, and writes to
consecutive bits of Fieldbus IN Area.
Byte (8-bit)
The 105G reads consecutive bytes
(8-bit values) from Fieldbus OUT
Area and stores each byte in the
most significant 8-bits of a
consecutive I/O register.
The 105G takes the most significant 8-bits
of consecutive I/O registers and writes
them to consecutive bytes (8-bit values) of
the Fieldbus IN area.
Word (16-bit)
The 105G reads consecutive words
(2x8-bit values) form Fieldbus
OUT Area and stores each word in
a consecutive I/O Register.
The 105G takes consecutive I/O registers
and writes them to consecutive words
(2x8-bit values) of Fieldbus IN Area.
4.9.2 Transfer Mode
Radio Interface registers are all 16-bit general-purpose input or output registers. That is, analog
inputs or outputs are stored as a 16-bit value. Digital inputs or outputs occupy a whole 16-bit
register and are stored as either 0000(hex) or FFFF (hex) for compatibility with the WIB-net
Radio Protocol. However, the Fieldbus Interface may contain (depending on the protocol)
significantly less registers than the Radio Interface (see diagram above). Also, certain protocols
may require a different I/O structure than that used by the Radio Interface registers.