Function Overview; Figure 7-1 Polling Operation Overview; Table 7-1 Polling Communication Specifications - Hitachi S10mini LQS070 Hardware Manual

7 COMMUNICATION FUNCTION

7.1 Function Overview

As a process communication (I/O communication) function, the D.Station supports
slave-style polling communication only. It does not support
bit-strobe/change-of-state/cyclic communication or peer communication. The term "process
communication" refers to a communication method for transmitting/receiving control data.
Table 7-1 shows the polling communication specifications.
No.
1 Communication style
2 User data length
3 Available ID
4 Data synchronicity assurance
5 Number of master units
<Polling operation overview>
The master node polls a slave node (D.Station) at fixed intervals. In this polling
request sequence, I/O data is transmitted to the slave, and the slave outputs the data to an
output module. The slave node transmits the data received from an input module to the
master by making a polling response to it. This operation is repeated at fixed intervals.
Polling request: Master's request of
I/O data and I/O data transmission
to slave

Table 7-1 Polling Communication Specifications

Item
One-to-one communication
Maximum transmission data length: 128 bytes (1024 points) + 4
bytes of additional information (optional)
Maximum reception data length: 128 bytes (1024 points)
No consideration need be given to the available ID.
2 bytes max. (The S10's I/O is basically in 2-byte units.)
One unit (MAC IDs of 0 through 63 are available).
Slave
D.Station
device
Slave
Polling response: I/O data
transmission from slave to
master

Figure 7-1 Polling Operation Overview

Polling communication specifications
Master
Slave
device
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