Maple Systems MAPware-100 - Manual (Page 21)

operator attempts to enter data outside the bounds, he will be notified with an error screen
indicating that the data is not within bounds. Data will not be sent to the PLC unless it falls
within the preset bounds.
Remember when linear scaling is set, the limits must be set in terms of the operator’s units
since the OIT converts the entered data into units the PLC is capable of dealing with. For
example, if the operator is to enter the temperature in degrees C, then the limits must be set in
degrees, not in A/D or D/A units that the PLC will actually use.
ASCII Table Button
When a register monitor is formatted as a binary ASCII string, a coil from the PLC is read
and, depending on the value of the coil, one of two ASCII strings will be displayed. This
allows the system programmer to customize the OIT to the particular application; instead of
simple On/Off indicators, the OIT may now display Running, or Stopped, or anything else
the system programmer thinks of. The OIT can store up to 30 ASCII strings, each of which
may be up to eight characters in length.
The method of cross-referencing the ASCII strings to coil values is fairly simple. The OIT
has a programmed table of 30 ASCII strings, each one unique. When a register monitor is
configured, use the ASCII Text box to select which string is displayed for a coil state of 0 and
1. The number of the ASCII string to be displayed is programmed into the OIT, so each
ASCII string may be used more than once and even to represent different coil states. The
following sample ASCII string table illustrates how the cross-referencing is accomplished.
The ASCII Table Editor allows the system programmer to enter custom ASCII strings that
represent the ‘0’ or ‘1’ states for any coil within the system. Since it is table-based (there is no
direct correlation between the coil state and a string), this allows the 30 strings to be
effectively used on many more than 30 coils. In many cases the system programmer has only
a few ‘off’ states such as stopped or off. This would only require one entry into the database,
leaving 29 entries for the ‘on’ state.
20 OPERATION
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