Topic: DMD0212
Configure Forces
Do-more controllers support true forcing of I/O points
and memory elements, which means that any I/O point or memory element
that is forced will not be changed from it's forced value by ladder logic
instructions or by an external communication request. All I/O points and
all writable memory elements (excluding structure fields) can be forced
to a constant value.
Forcing I/O points and memory elements is done through the force table that exists in the controller. This table contains a list of up to 250 entries, each of which is an element to force and the constant value to force that element to have.
Do-more Designer provides the Configure Forces dialog to manage the process of managing the list of elements in the force table. The Configure Forces dialog is invoked by the Debug-> Configure Forces menu item or by clicking the Forces button on the online toolbar.
Forced Elements - lists the elements in the force table
Element - the memory element being forced
Nickname - the memory element's nickname (if present)
Value - the constant value the element is being forced to
Add - invokes the Add Force dialog to add a new I/O point or memory element in the force table (see below)
Edit -
Delete - removes the currently highlighted I/O point or memory element from the force table
Delete All
- removes all of
Enable
Forcing in PLC - When the
first entry is added to the force table, this checkbox is automatically
checked, and will remain checked as long as entries remain in the force
table. Un-checking this box will leave the I/O points and memory elements
in the force table but the controller will not force the entries to their
specified constant values. Any time there are entries in the force table
and the Enable Forcing in the PLC is checked, the word
Display Hexadecimal and Octal Format in Addition to Native Format - enabling this option will add the hexadecimal and octal representations of the force value to the Value column.
Accept - saves any changes made to the force table to the controller then closes the Configure Forces dialog
Read PLC - reads the force table currently stored in the controller then displays those entries in the Configure Forces dialog
Cancel - does NOT save any changes made to the force table and closes the Configure Forces dialog
Clicking
the Add button will open the Add
Force dialog which is used to add a new I/O point or memory location and
it's force value into the force table. Clicking the Edit
button will invoke a similar dialog to modify the currently highlighted
entry that is already in the force table.
Element - enter the I/O point or memory element to add to the force table. This can be any I/O point or writable memory element (excluding structure fields) in the controller. Note: Use the F9 key (Element Browser) or Down-Arrow key (Auto-Complete), at any time to see a complete list of the memory locations that are valid in the current field of this instruction.
Force Value - the force value depends on the data type of the element as follows:
for Discrete I/O points and BIT-sized memory elements this field presents the option of OFF or ON
for Analog I/O points and numeric memory elements (Byte, Word, DWord, and Real), this field allows entry of any constant value or any symbolic constant
Any attempt
to close the project or disconnect from the controller with I/O points
or memory elements currently being forced will cause this dialog to be
displayed:
Open Force Configuration Dialog - opens the Configure forces dialog so that entries in the force table can be removed, or the Enable Forcing in PLC option can be unchecked to leave the entries in the table but stop forcing the entries to their constant values.
Close with Forces Active - disconnects from the controller, leaving the force table intact and force table processing in place.
Cancel - close the Attention! dialog and the programming session remains online
See Also:
Forcing I/O and Memory Items