Future Design MCTB 4.3, Руководство пользователя

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MCTB
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The
Continue automated program from last SP selection will resume the program from where it left off with
the last set point set by the program at the time of power failure.
The
Continue automated program from PV selection will resume the program using the current process value
at the time power is restored as the set point.
NOTE: ft continue from PV is selected and the recovery occurs on a ramp step, the ramp rate can be affected.
If only one loop is under program control, the time remaining in the step will be recalculated in order
to maintain the ramp rate that was programmed for the step based on the current PV value and the
target set point of the step. However, if two or three loops are under program control, all loops operate
under a common time base. Since the PV and target set point of each loop vary, the time is not
recalculated and each loop will continue ramping from its current PV value to its target set point in the
time remaining. This could result in a significant change in ramp rate for the remainder of the step.
The
Static mode selection will terminate the automated program and return the loop control to the single set
point mode of operation based on the “Setpoint at end of program” selection for the loop.
4.2.34 Communication Mode
The Communication Mode selection is used to specify how the loop control responds to a loss of
communications with the MCTB display. The communication mode selections are mutually exclusive, i.e.,
selecting one will turn off the other. Once the desired mode has been selected, press the “Done” button to set
the communication mode for the loop control board and return to the main Loop Configuration screen.
With the
Normal mode selection, the loop control will continue operation according to the last command given.
When power is first applied to the loop control, its outputs will activate immediately according to the last
commands given prior to power loss.
With the
Safety mode selection, all loop control outputs will be set to their minimum output state (according to
the value set in the output low limit setting) with event/alarm outputs turning off if there is a loss in
communications with the MCTB display that exceeds 60 seconds. Since the MCTB display provides the means
for control and monitor of loop operation, this ensures that any devices connected to the loop control outputs
will be shut down/turned off until corrections can be made to restore communications.
It also prevents the loop control outputs from activating when power is first applied until proper communication
is established with the MCTB display. This prevents any devices connected to the loop control outputs from
being activated until the runtime application has started which provides the user with access to the system
through the touch screen interface.