General Parameterization; Parameterization Of Modbus Master Tasks - Honeywell EK280 Applications Manual

EK280

8.2.1 General parameterization

Three parameter groups must be parameterized for operating the Modbus master.
1 The Modbus master task list:
The Modbus master task list contains up to 70 tasks. Each task consists of a register start address, the
number of registers and the access mode to the respective register(s).
There is only a single Modbus master task list in the device which is used together for all connections.
In the Modbus master task list (AL) only register start addresses can be used which are present in the
standard Modbus table ( chapter 8.1.1).
2 The Modbus master parameters (Modbus master info):
There are 8 Modbus master info instances. In each of the 8 possible connections, it is possible to refer
to another Modbus master info instance. However, an instance may also be used more than once. The
Modbus master info contains the index of the task list and the number of tasks to be processed from
this index.
3 A link:
A minimum of one link from a possible 8 must be parameterized for Modbus master operations.
Amongst other things, the (trigger) event is established in this link which should lead to the construction
of this link. The link contains a reference to the instance of the corresponding Modbus master info.
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As only register start addresses which are present in the standard Modbus table can be used in
the Modbus master task list ( chapter 8.1.1) then before setting up Modbus master operations
this standard Modbus table must always be correctly parameterized first.
Fig. 17 gives an overview of the dependencies of parameterization:

8.2.2 Parameterization of Modbus master tasks

It is established via the Modbus master task list which and how much data shall be read or written. This
Modbus master task list, just like the standard Modbus table ( chapter 8.1.1) contains a maximum of
70 entries (instances).
There is only one Modbus master task list for the whole device. Various links can be parameterized, which
due to various events access different parts of the Modbus master task list via the parameterized Modbus
master info instance. The corresponding part of the Modbus master task list must therefore be parameterized
for each of these events. Parts of the Modbus master task list can also belong to several connections.
Application Manual
Fig. 17: Dependencies within Modbus master parameterization
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