Configuration via Web Interface
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State values mapping
State input values are intended be mapped onto input MODBUS registers. You are required to
verify that the discrete variable to be mapped actually has an input value with a state format.
A state input value (16 bits) is always mapped onto a single input register (16 bits).
Output Variables Mapping
Packed values mapping
Packet output values are intended be mapped onto coils MODBUS registers. You are required
to verify that the discrete variable to be mapped actually has an output value with a packet
format.
Packet output values must be mapped 1 byte at a time, i. e., the minimum mapping unit
consists of 8 Boolean values, as stored in the LSB or MSB part of the discrete variable.
MODBUS coils registers consist of a single-bit. In order to preserve the byte alignment, the
register number used for mapping must always refer for the 1st bit within a byte
(0, 8, 16, 24
…
).
State values mapping
State output values are intended be mapped onto holding MODBUS registers. You are required
to verify that the discrete variable to be mapped actually has an output value with a state
format.
A state output value (16 bits) is always mapped onto a single holding register (16 bits).
Automatic Mapping of MODBUS Input Registers
Each HART device is mapped on 12 consecutive MODBUS input registers. The input registers
can be read using MODBUS function code 04 (Read Input Registers). In general, the
information about the
Wireless
HART gateway is mapped on registers 30001 ... 30012. The
first device is mapped on register 30013, the second starting at register 30025, and so on.
The order of the HART device mapping starting from register 30001, is the same as the order of
the HART devices returned by the command 84 (HART CMD 84, Read Sub-Device Identity
Summary). For example, the HART device that you can read by using CMD 84 with the sub-
device index = 1 is mapped starting at register 30013. The device that you can read by using
CMD 84 with the sub-device index = 2 is mapped starting at register 30025 and so on.
To find out the starting register of a certain sub-device, use the following formula:
SIR = 30001 + 12*(SDI) where SIR is the starting input register of the associated HART device
and SDI is the CMD 84 sub-device index value.
The following table shows the exemplary mapping of the first 2 HART devices, for example the
ones associated with SDI = 1 and SDI = 2.
Note!
Output Variables Mapping: User/Host Application Responsibilities
You can still map state values on a different MODBUS register type, i. e., on the holding
register.
However, you are required to ensure the correct behavior of the MODBUS master.
