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MELSEC-Q
3 SPECIFICATIONS
3.5.6 Expansion relay (EM0 to EM1023)
The expansion relay is a relay that can be used to send and receive ON/OFF data
between tasks internally in the QD51 (-R24).
(1) Turning the expansion relay ON and OFF, and reading ON/OFF
data
(a) The special variable B@ can be used in a BASIC program to turn the
expansion relay ON and OFF and to read ON/OFF data.
Expansion
Relay
QD51(-R24)
Programmable
controller
CPU
TO
(Writing of data)
FROM
(Reading of data)
BASIC
program
B@
(Reading ON/OFF data)
B@
(Writing ON/OFF data)
(b) During BASIC program execution by multitasking, either task can read the
ON/OFF data, and this register can be used by either task through a BASIC
program.
Expansion Relay (EM)
EM0 : ON
Task
1
Task
2
EM0
ON/OFF
EM0 ON/OFF
Reading of data
(2) Number of Expansion Relay Points
The QD51 (-R24) expansion relay has 1024 points.
REMARK
For details on special variable B@, refer to the Programming Manual (Commands).
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