Allen-Bradley MicroLogix 1200 Reference Manual page 342

22-10 Data Logging (MicroLogix 1500 1764-LRP Processor only)
Publication 1762-RM001C-EN-P
File Size (FSZ)
File Size (FSZ) shows the number of records that are allocated for this
queue. The number of records is set when the data log queue is
configured. FSZ can be used with RST to determine how full the queue is.
To address this word in ladder logic, use the format: DLS0:Q.FSZ, where
Q is the queue number.
Records Stored (RST)
Records Stored (RST) specifies how many data sets are in the queue. RST
is decremented when a record is read from a communications device. To
address this word in ladder logic, use the format: DLS0:Q.RST, where Q is
the queue number.
If a queue is full and another record is saved, the oldest
NOTE
record is over-written. Queue behavior is the same as a
FIFO stack—first in, first out. If a queue is full and an
additional record is saved, the "first" record is deleted.
DLS information can be used in the following types of instructions:
Instruction Type
Relay (Bit)
Compare
Math
Logical
Move
Operand
Destination Output Bit
Source A
Source B
Low Limit (LIM instruction)
Test (LIM instruction)
High Limit (LIM instruction)
Source (MEQ instruction)
Mask (MEQ instruction)
Compare (MEQ instruction)
Source A
Source B
Input (SCP instruction)
Source A
Source B
Source