4. Configuration
90
Write Mask of IEC
Variables
Initial address of the variables for the
write mask (%Q)
Table 4-55. Device Mapping
Notes:
Function: the available data types are detailed in the Table 4-48 and MODBUS functions (CF) are
available in the Table 4-50.
Polling: this parameter indicates how often the communication set for this relation must be executed.
At the end of communication will be awaited a time equal to the configured polling and after, will be
performed a new communication as soon as possible.
Mapping Diagnostics Area: this field is limited by the size of output variables addressable memory
(%Q) at CPU, which can be found in the chapter Technical Description. The configured MODBUS
relations diagnostics are described in Table 4-51.
Read/Write Data Size: details of the data size supported by each function are described in the notes
of the section Configuration of the Relations – Symbolic Mapping Setting.
Read IEC Variable: if the MODBUS data type is Coil or Input Status (1-bit), the initial address of
the IEC reading variables will have the format %IX10.1, for example. However, if the MODBUS
data type is Holding Register or Input Register (16-bit), the initial address of the IEC reading
variables will be %IW. This field is limited by the size of input variables addressable memory (%I) at
CPU, which can be found in the chapter Technical Description.
Write IEC Variable: if the MODBUS data type is Coil, the initial address of the IEC writing
variables will have the format %QX10.1, for example. However, if the MODBUS data type is
Holding Register (16-bit), the initial address of the IEC writing variables will be %QW. This field is
limited by the size of output variables addressable memory (%Q) at CPU, which can be found in the
chapter Technical Description.
Write Mask: the function Write Mask (FC 22) employs a logic between the value already written
and the two words that are configured in this field using %QW(0) for the AND mask and %QW(2)
for the OR mask; allowing the user to handle the word. This field is limited by the size of output
variables addressable memory (%Q) of each CPU, which can be found in the chapter Technical
Description.
Default Value: the factory default value cannot be set for the Mapping Diagnostic Area, IEC
Reading Variable, IEC Writing Variable and Writing Mask fields, since the creation of a relation can
be performed at any time on application development. The MasterTool IEC XE software itself
allocate a value from the range of direct representation output variables (%Q), still unused. Factory
default cannot be set to the Reading/Writing Data Size fields, as they will vary according to the
MODBUS data type selected.
ATTENTION:
Unlike other tasks of an application, when a mark is reached at MainTask debugging, the MODBUS
RTU Master instance task or any other MODBUS task will stop being executed at the moment it
tries to write in the memory area. This occurs in order to maintain data consistency of memory areas
while MainTask is not running.
MODBUS RTU SLAVE
This protocol is available for the Nexto Series on its serial channels. At selecting this option in
MasterTool IEC XE, the CPU becomes a MODBUS communication slave, allowing the connection
with MODBUS RTU master devices. This protocol is available only in execution mode (Run Mode).
There are two ways to configure this protocol. The first one makes use of direct representation (%Q),
in which the variables are defined by your address. The second one, through symbolic mapping,
where the variables are defined by your name.
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General