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(5) Checking loopback execution status
Whether loopback is being performed or not can be checked through link special relay (SB) and link special
registers (SW). ( Page 124, CHAPTER 9)
1. While loopback is performed, Loopback status (SB0065) is on.
2. Loopback station numbers are stored to Loopback station number (SW0070 and SW0071).
Loopback when a cable is disconnected between station No. 2 and stations No. 3
SW0070 and SW0071 store "2" and "3", respectively.
Remark
If the master station is powered on before slave stations, data link may be reconfigured. During the reconfiguration
(maximum 13 seconds), an error is detected using SB00B0.
Starting up the master station last can prevent data link from being reconfigured.
(6) Checking communication error and network event history
Communication errors and network events are detected by CC-Link IE Field Network diagnostics, but can also be
detected through link special relays (SB) and link special registers (SW). ( Page 124, CHAPTER 9)
1. The number of communication errors is stored in SW0074 to SW0077, and SW007C to SW007F.
The number can be cleared by Clear communication error count (SB0006).
2. When network event history occurs, Event history status (SB007A) is turned on. Number of
network event history items is stored in Event history cumulative count (SW007A). The number
can be cleared by Event history count clear (SB0009)
No. Description No. Description
SB0065 Loopback status SW0070 Loopback station number 1
SW0071 Loopback station number 2
Number Description Number Description
SB0006 Clear communication error count
SB0009 Event count clear
SW0074 PORT1 cable disconnection detection count
SW0075 PORT1 receive error detection count
SW0076 PORT1 total no. of received data (lower 1 word)
SW0077 PORT1 total no. of received data (upper 1 word)
SB007A Event history status SW007A Event count
SW007C PORT2 cable disconnection detection count
SW007D PORT2 receive error detection count
SW007E PORT2 total no. of received data (lower 1 word)
SW007F PORT2 total no. of received data (upper 1 word)
Ex.
Station No. 0 Station No. 1 Station No. 2 Station No. 3