9DEDICATED INSTRUCTIONS

Function

MELSEC-Q

(1)Data stored in the device designated in (S2) and succeeding devices are sent according to the control data of the device designated in (S1) and succeeding devices, via the on-demand function of the MC protocol of the module designated in Un.

QCPU

Q series C24

b15 to b0

(S2)+ 0

+ 1 Channel 1

+ 2

Channel 2

Channel to be

used is set by

the control data.

Send

Send

(2)When an ONDEMAND instruction is executed on a channel, other ONDEMAND instructions cannot be executed on that channel at the same time.

If an attempt is made during execution of an ONDEMAND instruction to execute another ONDEMAND instruction, the second instruction will not be executed until the execution of the first instruction is completed.

(3)Whether an ONDEMAND instruction was completed normally or abnormally can be checked by the completion device ((D)) or status display device at completion ((D)+1).

(a)

Completion device

: Turns on at the END processing of the scan where

 

 

the ONDEMAND instruction is completed, and turns

 

 

off at the next END processing.

(b)

Status display device

 

 

at completion

: Turns on and off depending on the completion status

 

 

of the ONDEMAND instruction.

 

 

• Normal completion : Off with no change.

 

 

• Abnormal completion: Turns on at the END

 

 

processing of the scan where

 

 

the ONDEMAND instruction

 

 

is completed, and turns off at

 

 

the next END processing.

[Operation during execution of an ONDEMAND instruction]

Sequence

END

 

END

END

 

END

processing

 

processing

processing

processing

program

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Execution of ONDEMAND

 

 

Completion of reading user frame

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

by ONDEMAND instruction

 

 

 

 

 

 

instruction

 

 

ONDEMAND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

instruction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Completion device

OFF

 

 

 

 

 

Abnormal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ON

completion

Status display device

OFF

 

 

 

 

 

 

 

 

 

 

 

at completion

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Normal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

completion

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

One scan

 

 

 

 

 

9 - 3

9 - 3