Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 29

1 OVERVIEW
I50
Interrupt
sequence
program
IRET
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(c) The interrupt sequence program of the host's CPU module can be started
up using the event issue function. This function reduces the response time
of the system and process real-time data receiving. (Refer to Section 7.5,
"Starting Up the Interrupt Sequence Program.")
CPU module
MAIN
Conditions
Normal
matched
sequence
program
END
(4) Enhanced RAS functions (Refer to Section 3.2.2, "RAS function.")
(a) By using the control station switch function, if the control station of the
network is down, a normal station is substituted for the control station,
enabling to continue the network communication.
(b) When a faulty station recovers and can resume normal operation, it
automatically returns to the network to resume the data communication
using the automatic return function.
(c) The automatic return control function allows a failed control station to be
reconnected to the network as a normal station, reducing network downtime.
(d) The loopback function (in the optical loop system) isolates a faulty part,
where a fault such as cable disconnection or a station error has occurred,
and enables data communications among operable stations.
(e) Preventing station failure using external power supply
When two or more stations are faulty and halted in the optical loop system,
stations between these faulty stations can continue the data link.
Because the loop back is prevented, the link scan time will be stabilized.
(The QJ71LP21S-25 is the network module where external power can be
supplied.)
Network module
Condition check
Interrupt condition
parameters
• Relay information
• Register data
• Arrival at a channel
• Network status
MELSEC-Q
MELSECNET/H
Transient transmission
from other station
Cyclic transmission
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