OM-550
u
15
u
2.4 PROGRAMMED FEATURES
There are special programmed features that support the operation of the OM-550.
These features are described in the following sections.
2.4.1 DATA CACHE
The OM-550 contains a 28 Kbyte data cache that retains its data even when the unit is
“OFF”. Each data point occupies four bytes of cache memory; thus the capacity of the
cache depends upon the quantity of active (unskipped) channels.
ACTIVE CHANNELS
CACHE CAPACITY
1
7000 scans
2
3500 scans
3
2333 scans
4
1750 scans
5
1400 scans
When the RUN or PROG keys are pressed, the cache is automatically erased. Do
not press RUN or PROG until the data has been transferred to a PC, otherwise it
will be lost.
During a Manual Reset, 100 "phony" data readings will automatically be logged to the
cache, as CH 1 & CH 2 data. The statistics for this artificial data can be viewed by
pressing the
STOP
key after executing a Manual Reset, explained in
APPENDIX A:
CALIBRATION
.
The artificial data is a functional test of the unit and can also be used to ensure that the
RS-232 port connection to a PC is functioning properly. When the data is transferred to
a PC, it will graph as a straight line with constant, increasing slope.
The Math channel data is not saved to cache. It is calculated and "transferred" to
the PC durring upload (refer to section
4.5 MATH PSEUDO-CHANNEL
for more
information).
