Polled Data; What Is Polled Data; Devicenet Data Format - Control Techniques UD77 User Manual

5

Polled Data

The default DeviceNet configuration contains three 16-bit IN data words
and three 16-bit OUT data words. These data words are classed as
"polled data channels".
NOTE
"OUT data" and "IN data" describe the direction of data transfer as
seen by the PLC scanner.
5.1

What is Polled Data??

Polled data is a method data transfer that must be set-up during
network configuration,
configuration is complete. The high-speed data transfer is achieved by
transmitting only a 16-bit data value for each polled channel over the
DeviceNet network, and relying on local mapping information within the
Unidrive to ensure the correct data is sent to the correct locations. This
method relies on the PLC program writing and reading data values to
and from the registers allocated to the node during network
configuration, and the source and destination of IN and OUT data being
set-up correctly in the Unidrive itself.
The flexibility of the Unidrive DeviceNet interface means that each
polled data OUT channel can be directed to any read-write Unidrive
parameter. Similarly, each polled data IN channel can use any Unidrive
parameter as a source of data.
NOTE
The mapping configuration cannot be changed dynamically, as the
UD70 must be reset before changes to the mapping become active.
5.2

DeviceNet Data Format

The Unidrive DeviceNet interface has a data format of 3 polled data
words. Explicit data must be used for non-cyclic communications.
Non-cyclic
mode
Explicit
Issue Number: 2
but is transmitted
Polled Comments
words
3 This is the same data format as Mentor II,
and Format 0.03 on Commander SE
automatically once
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