IDEC High Performance Series - Manual (Page 572)

Chapter 3
554
External Device Setup Manual
4 Communication Status Confirmation
4.1 Master Error Processing
The master does not display O/I Link errors. To monitor for errors, compare LSD102 and LSD104. If they are different, it indicates
that there is a communication problem.
In the case of PLC Link communication with the PLC, errors are displayed and the error information is written to the System Area.
4.2 Slave Error Processing
When a slave is not engaged in O/I Link communication with the master, Network Offline is displayed in the center of the screen. The
screen is cleared when communication starts.
4.3 Status of a Slave in the O/I Link
If a slave unit does not exist or fails to engage in normal communication even though the slave is registered in the Slave Registration
Setting Register (LSD102 in the master), the status of the slave is referred to as “offline” status.
Conversely, the status of the slave in which normal communication is executed is referred to as “online” status.
When a slave unit is in offline status, the master always monitors the slave status if it is online. In one cycle, the master searches for
one slave unit in the offline status after the master completes the communications with all slave units in online status. Two sets of O/
I cycle periods are required in order to recognize two slave units in offline status.
Fig. When 2 slave units are in offline status:
The numbers in () indicate the processing sequence.
The Time Out duration for the command that detects the presence/absence of a slave (hereafter referred to as a handshake command)
is set to 30 msec on the master.