App - 3                          App - 3 
MELSEC-Q
PPENDI
 
 
(2)   Communications specifications 
Data bit and stop bit settings differ. 
Correct the BASIC program. 
 
 AD51H-S3  A1SD51S QD51(-R24) 
Data bit  5, 6, 7, 8  5, 6, 7, 8  7, 8 
Stop bit 
1, 1.5, 2 
1, 1.5, 2  1, 2 
 
(3)   Common memory backup 
Common memory backup is as shown below. 
 
 AD51H-S3  A1SD51S QD51(-R24) 
Common Memory 
Backed up 
Backed up  Not backed up 
 
In the QD51 (-R24), common memory is not backed up by a battery. If backup is 
necessary, use the programmable controller CPU's file register (R). 
Replace the part of the BASIC program, which is used for reading or writing the 
common memory by the GETMEN/PUTMEN command, with the one for reading 
or writing the file register (R) by the PCRD/PCWT command. 
 
(4)   Task start signal (Y19) 
If the task start signal (Y19) has been used to start a task, add the exclusive 
command YCHECK. 
In the A1SD51S or AD51H-S3, a task starts as an interrupt to the module when 
the task start signal (Y19) turns ON. 
As the QD51 (-R24) monitors the task start signal (Y19) at 10ms intervals to start 
tasks, the start timing is different between the QD51(-R24) and the A1SD51S or 
AD51H-S3. Executing the dedicated YCHECK command as shown below makes 
the start timing the same as the A1SD51S or AD51H-S3. 
 
Specify Task start.
Specify Task 1.
Start
Execute Y check.