Hitachi HIDIC EH-150 Applications Manual page 13

3. Four Types of I/O Message Communication Protocol
It is possible to select the optimal communication mode for a given network configuration according to the
features of each device.
Please choose the communication method which is appropriate to the good point of each device.
But each device may not support a partial communication method.
Therefore, for the details, refer to the manual of each device.
I/O
Features
communication
Used when transferring any size of I/O data
between the master and a slave.
Polling In this mode, data is communicated between the
master and a single specific slave (point to point).
Most of the devices are supporting this method.
Used when transferring small amounts of input
data between the master and a slave.
Bit Strobe It is possible to return up to 8 bytes of input data
in response to a request from the master, from
each slave to the master.
Used when transferring any size of I/O data
between the master and a slave.
In this mode, data is communicated between the
Cyclic master and a single specific slave at fixed time
intervals specified by the user.
This mode makes it possible to alleviate the traffic
in the network in this way.
Used when transferring any size of I/O data
between the master and a slave.
In this mode, data is communicated between the
Change of State master and a single specific slave when the data is
(COS) updated or at fixed time intervals specified by the
user.
This mode makes it possible to alleviate the traffic
in the network in this way.
Table 2.1 DeviceNet I/O communication method
2-2
Chapter 2 Features
EH-RMD EH-IOCD
: supported
×
: not supported
Discrete
I/O
×
×
×