Mitsubishi Electric MELSEC IQ-R series Reference Manual page 294

Free cluster table
A data indicating the status of cluster usage. It is a response data to 'read drive memory usage status' (command: 0205).
■Data communication in ASCII code
The numerical value that indicates usage status is converted to n-digit (hexadecimal) ASCII code and sent to the external
device. (16 clusters/4 digits)
■Data communication in binary code
An m-byte numerical value that indicates usage status is sent to the external device. (16 clusters/2 bytes)
■Content of free cluster table
The usage status of each cluster is indicated by one cluster per bit.
Ex.
0: Empty, 1: Used
Cluster b15
*1
First 16 clusters 0

0
 

0
*3
Last 16 clusters 0
*1 16th cluster from the head cluster
*2 First cluster
*3 Last cluster
When the usage status is as shown above, the content of free cluster table that is returned to the external device is as follows:
• When 32 clusters are returned while communicating in ASCII code
'3CFF003F' is returned and it is sent from '3'.
• When 32 clusters are returned while communicating in binary code
'FFH', '3CH', '3FH', and '00H' are returned and these are sent from 'FFH'.
■Drive memory defragmentation
When performing defragmentation of drive memory, the free cluster table is not returned.
15 QnACPU DEDICATED COMMANDS
292
15.2 Defragmentation of Drive Memory
b14 b13 b12 b11 b10
0 1 1 1 1
0 0 0 0 0
    
0 0 0 0 0
0 0 0 0 0
b9 b8 b7 b6 b5
0 0 1 1 1
0 0 0 0 1
    
0 0 0 0 0
0 0 0 0 0
b4 b3 b2 b1 b0
*2
1 1 1 1 1
1 1 1 1 1
    
0 0 0 0 0
0 0 0 0 0
Values for 16 bits
3CFFH
003FH

0000H
0000H