Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual - Manual (Page 201)

EAF Logarithmic, Trigonometric
and FIFO Instructions
Chapter 15
15-8
Bits 14-17 of the result word are reserved for status bits:
This Bit: Stores this:
14 file empty indicator
1 file is empty
0 file has data
You cannot unload data from an empty file. If the FIFO file is empty, there
is no data to unload. Use this bit to condition a FIFO Unload.
15 file full indicator
1 file is full
0 file has data
You cannot load data after the FIFO file is full. If you attempt to load any
data it will be lost. As soon as you unload the first word, the bit resets (0).
Use this bit to condition a FIFO Load.
Data transfers with a false to true (0 to 1) transition of the EAF rung. You
can monitor this transition with bits 16 or 17.
16 unload enabled
1 FIFO is enabled
0 FIFO is not enabled
17 load enabled
1 FIFO is enabled
0 FIFO is not enabled
Important: The FIFO Load and FIFO Unload instructions must have the
same File Address, Result Address and File Length. Data is loaded into
and unloaded from the same addressed file.
You can enter a ladder diagram for executing FIFO Loads and FIFO
Unloads by entering a ladder diagram like that in Figure 15.8. This figure
identifies all words and certain bits used in FIFO Load and FIFO Unload.
Rungs 2, 3, 4 and 6 are included as display rungs and are not necessary for
proper FIFO operation.