Toshiba DeviceNet nv Series, Инструкция по эксплуатации, Страница: 26 / 159

Chapter 1 DN611B Introduction
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1.5
Basic functions
This section describes the following two methods, which are communication functions between the DN611B
and slave devices.
1.5.1 Poll command / response method
1.5.2 Bit-strobe command / response
1.5.1
Poll command / response method
The poll command / response method is used to input / output an arbitrary amount of data between a master
device and a slave device.
The master device has in its own station information on each slave device on the network (list of node
addresses, input / output data amount, etc.: scan list). In the case of a poll instruction, the master device
outputs an arbitrary amount of data to each slave device based on this information.
The slave device sends response data (arbitrary amount of data) to the poll command to the master device
(poll response). How the slave device interprets the poll command and what data is sent in the poll response
depends on the specifications of the slave device.
As a matter of course, this communication function requires that the slave device support the poll command /
response method (slave devices on the DeviceNet almost support this method).
(1) Poll command
In the example in Figure 1-7, the DN611B polls the sensor, inputs sensor data, and sends output control data
to the actuator. To write polling output data from the controller to DN611B, use network variables. See Chapter
4 for settings.
Figure 1-7 Example of Poll command / response method
Controller
Slave 1
Proximity sensor
NA = 19
DeviceNet
Poll command
Poll response
NA (node address):
Node identification number of DeviceNet devices
connected to one DeviceNet network.
Values range from 0 to 63 in decimal.
In DeviceNet, the node addresses of devices connected to
one network must be different values.
Master
DN611B
NA = 1
Slave 3
Photoelectric sensor
NA = 22
Slave 5
Actuator
NA = 52