LINK Systems System 1100 Tonnage Monitor - Manual (Page 48)

THEORY OF OPERATION
___________________________________________________________________
3-11
3.5.2 Automatic Zeroing by Position
The second method of automatic zeroing provided on a System 1100
Tonnage Monitor is zeroing by position (cam zeroing). A cam switch
or limit switch adjusted to be closed when the machine ram or slide
is in a region where no force is generated by tooling "tells" the
automatic zero circuit when no load is on the machine, allowing the
circuit to be activated. The cam or limit switch opens before the
tooling closes in the downstroke to turn off the zero circuit and
capture the peak load signal. The cam or limit switches close
again on the upstroke after tooling and stripper forces are over to
resume zeroing.
3.6 Data Windows
Peak tonnage monitors capture the maximum tonnage seen by each
strain gauge. This maximum tonnage is used for comparison to
setpoints in determining if an alarm should be generated to stop
the production process. While this is adequate for most
applications, complex tooling can produce multiple peaks resulting
in only the greatest peak being checked against setpoints. Where
closer monitoring is desired in these applications, System 1100
Tonnage Monitors provide four Data Windows to monitor up to four
additional peaks other than the absolute maximum peak tonnage.
These additional peaks are referred to as 'local' peaks. The
position of the local peaks is determined by external cam switches
connected to the System 1100 data window inputs, labeled DW1, DW2,
DW3, and DW4.