Mitsubishi Electric MELSEC iQ-R Series User Manual page 73

Program that detects loopback station numbers (master operating station only)
By detecting loopback station numbers, a faulty station can be found. Whether loopback is being performed or not can be
checked using 'Network topology setting' (SB0078) and 'Loopback status' (SB0065) of the master operating station.
Ex.
Program that stores loopback station numbers to 'wLoopbackStationNumber_1' (D1000) and 'wLoopbackStationNumber_2'
(D1001)
Classification Label name
Module label GN11_1.bSts_DataLinkError
GN11_1.bOpe_Loopback
GN11_1.bSet_RingTopology
GN11_1.wnVal_LoopbackStationNumber[1]
GN11_1.wnVal_LoopbackStationNumber[2]
Label to be defined Define global labels as shown below:
(3) When 'Network topology setting' (SB0078) and 'Loopback status' (SB0065) are on, 'Loopback station number 1' (SW0070) and 'Loopback station number 2'
(SW0071) are saved.
Precautions
■Supported version
To use the loopback function, check that all stations support ring topology. ( Page 320 Added and Enhanced Functions)
■Loopback function setting and network configuration
To use the loopback function, configure the network in ring topology and set "Network Topology" to "Ring" in "Basic Settings"
of the master station. If "Network Topology" and the network configuration are inconsistent, an error may occur in all stations
and data link cannot be performed.
■When a loopback occurs or a loopback is resolved
Due to the occurrence or resolution of a loopback, transient transmission may become temporarily impossible. The following
shows the periods of time until transient transmission becomes possible again.
• A period of time until transient transmission becomes possible after the occurrence of a loopback: Maximum 1.1 seconds
• A period of time until transient transmission becomes possible after the resolution of a loopback: Maximum 1.3 seconds
Transient transmission executed at the time of the occurrence or resolution of a loopback may be completed with an error. In
such a case, execute transient transmission again. For a dedicated instruction, set transient transmission so that it will not be
completed with an error by increasing the number of resends or extending the monitoring time.
Description
Data link error status of own station
Loopback status
Network topology setting
Loopback station number 1
Loopback station number 2
1
Device
SB0049
SB0065
SB0078
SW0070
SW0071
1 FUNCTIONS
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1.5 RAS