Mitsubishi Electric MELSEC Q Series Programming Manual page 52

Maximum number of array elements
The maximum number of array elements differs depending on data types as shown below.
Data type
Bit, word (signed), word (unsigned)/16-bit string, timer, counter, and retentive timer
Double word (signed), double word (unsigned)/32-bit string, single-precision real, and time
Double-precision real
String
4 PROGRAM CONFIGURATION
50
4.4 Method for Specifying Data
Maximum number
32768
16384
8192
32768  divided by string length