Overview; Communications Continuation For Controller Link Unit Errors - Omron SYSMAC CS1W-CLK13 Operation Manual

Overview

8-1 Overview
Note
8-1-1

Communications Continuation for Controller Link Unit Errors

Overview
Normal Operation
200
By mounting the CS-series Optical Ring Controller Link Units (CS1W-CLK13/
12-V1 or CS1W-CLK53/52-V1) to the CS1D System, Controller Link Units can
be used in duplex operation. The duplex function for Communications Units is
used in token-ring mode.
1. Use duplex communications systems in token-ring mode. Token-ring
mode's transmission path duplication and the CS1D System's duplex func-
tion for Communications Units allow the creation of a highly reliable net-
work. If used in token-bus mode, the network will be temporarily split into
two networks when Controller Link Units are replaced online because the
transmission path is not duplicated.
2. If an error occurs in an active Controller Link Unit and there is an active/
standby switchover, or if an active Controller Link Unit is replaced online,
because the relevant node will temporarily leave and then re-enter the net-
work, communications operations (both message communications and
data links) will be temporarily stopped. At this time, the Data Link Partici-
pation Flag for the relevant node will turn OFF, and the Communications
Error Flag will turn ON. After the switchover, communications will resume
and everything will return to the normal state (the Data Link Participation
Flag turns ON and the Communications Error Flag turns OFF). For this
reason, perform the following processing in systems where there are du-
plex nodes in the network.
• When using message communications, set the number of retries for
the SEND, RECV, and CMND instructions (i.e., set the number of re-
tries in the control data to a value other than 0), and be sure to perform
resend processing for instructions.
• When using data links, while communications operations are stopped,
data will not be sent or received for the relevant node. (Data sent or
received, however, via data link immediately before communications
stopped will be saved.) Therefore, if necessary for the application, in-
clude processing to control whether data received via data link after
communications resumes (i.e., when the Data Link Participation Flag
changes from OFF to ON and the Communications Error Flag chang-
es from ON to OFF) is enabled or not. (Include processing in the ladder
programs for the CPU Units at the relevant node and the data link des-
tination node).
A theoretical value for the time required for communications to resume can
be obtained using an equation. (Refer to 8-5 Switching Time for Duplex
Units.)
By using Duplex Controller Link Units, if there is an error in one of the Control-
ler Link Units that causes it to stop operation, the other Controller Link Unit
can continue communications.
Set the same unit number and node address for a Controller Link Unit
mounted to the same CS1D System.
Normally, one Unit performs communications operations in active mode. The
other Unit waits in standby mode without participating in the network. The
standby Controller Link Unit continuously performs internal self-diagnosis.
Section 8-1