
A.TROUBLESHOOTING APPENDIX B-64014EN/03
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A.1 CHECKING COMMUNICATION WITH A HUB
(1) Make sure that the STP cable between the hub and the FAST
Ethernet/FAST Data Server is connected.
(2) Make sure that cables are properly wired.
• Though communication is carried out when the cable pair at
the send and receive sides is not properly mounted,
communications errors may occur more frequently.
(3) Make sure that a hub for 100BASE-TX is used.
• A hub for 10BASE-T may be used to perform
communication. In this case, however, the communication
speed can decrease.
(4) Make sure that the LIL LED on the FAST Ethernet/FAST Data
Server is lit at all times.
• The LIL LED will not light if the FAST Ethernet/FAST
Data Server is not connected to the hub or if the hub is not
ON.
(5) Make sure that the LED (LINK indicator LED) on the connected
hub is lit at all times.
• Some hubs do not have a LINK indicator LED.
• The LINK indicator LED will not light if the hub is not
connected to the FAST Ethernet/FAST Data Server or the
CNC is not ON.
(6) Make sure that a hub for full duplex communication only is not
used.
• The FAST Ethernet/FAST Data Server automatically
detects the communication speed and communication mode
(full duplex or half duplex) by using the auto negotiation
function. In communication with a hub that does not have
the auto negotiation function, the FAST Ethernet/FAST
Data Server recognizes the communication speed correctly
but regards the communication mode as half duplex
communication.
As a result, when an attempt is made to communicate with a
hub for full duplex communication only that does not have
the auto negotiation function, there is a discrepancy in
communication mode, so correct communication cannot
sometimes be performed.
• For details on how to connect, see Part V "CONNECTION."