Dedicated Communication Master (Communication Between Cnets); Introduction - LG GLOFA-GM Series User Manual

Chapter 7 Communication function
7.3 Dedicated communication master (communication between Cnets) Ver.2.0

7.3.1 Introduction

Dedicated communication master provides Function Block service for communication between Cnet I/F modules
available only for Cnet Ver.2.0 or later. Dedicated mode in the former Cnet I/F modules than Ver.2.0 has only slave
function, thus, for communication between GLOFA Cnets, one Cnet I/F module shall be set to user mode and the
other shall be set to dedicated mode to define the frame in Frame Editor by setting the user mode station to master
station and to additionally prepare program via SEND/RCV Function Block in GMWIN program inconveniently.
However, without user's additional protocol definition during the communication between GLOFA Cnets dedicated
communication master function allows communication between Cnets using only Function Block for dedicated
communication with master function added to dedicated mode and it has following characteristics.
Master function added to dedicated mode slave function.
Same mode switch in dedicated mode is used with Function Block added for master function.
No need to prepare frame via Frame Editor after setting the dedicated mode. Communication is available
by preparing program via dedicated communication Function Block in GMWIN.
Programming available for each RS-232C/RS-422 channel.
Cnet I/F module available for communication in dedicated mode slave can be used in a former module than
Ver.2.0.
Reading/Writing of continuous data of max. 110 bytes are allowed via one Function Block using
Reading/Writing commands of continuous blocks of dedicated communication protocol.
Service result can be checked via NDR/ERR output of Function Block.
For communication with multi-stations in RS-422 channel, programming is necessary to allow
communication in order in GMWIN program so to protect the crash error of data.
All Cnet I/F modules operated as master/slave are set to dedicated mode.
Module operated as master is allowed only for 1 station.
Remark
[Note 1] Only one station among Cnet I/F modules connected via dedicated mode must be set to master station.
Namely, Function Block for dedicated communication shall be used only in one station. If several masters
are applied, normal communication is unavailable due to data crash in communication line.
[Note 1]
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