Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 41)

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 41
Detailed Drive Operation Chapter 1
Digital Output On/Off Delay Timers
Each digital output has two user-controlled timers associated with it. One timer
(the On timer) defines the delay time between a False to True transition
(condition appears) on the output condition and the corresponding change in
state of the digital output. The second timer (the Off timer) defines the delay
time between a True to False transition (condition disappears) on the output
condition and the corresponding change in the state of the digital output. Either
timer can be disabled by setting the corresponding delay time to 0.
Direction Control and
Bipolar Reference The direction of rotation of the motor can be controlled by a forward/reverse
command or by the use of a bipolar signal. Parameter 153 [Control Options], bit
0 “Bipolar SRef ” selects this option.
When this bit is enabled (1) a bipolar speed reference is used. In bipolar reference
mode, parameter 40 [Selected Spd Ref ] indicates both the speed magnitude and
the direction: Positive (+) speed reference values = forward direction and
negative (–) speed reference values = reverse direction. When this bit is disabled a
unipolar speed reference is used. In unipolar mode, the speed reference is limited
to a minimum value of zero (0), shown by the “Max” selection block (in the
diagram below). In this case parameter 40 [Selected Spd Ref ] supplies only the
speed magnitude. The direction is determined by parameter 152 [Applied
LogicCmd] bits 20 “Forward” and 21 “Reverse”. The forward/reverse direction
button on the HIM is one possible source for the [Applied LogicCmd] direction
IMPORTANT Whether a particular type of transition (False-True or True-False) on an
output condition results in an energized or de-energized output depends
on the output condition. If a transition on an output condition occurs and
starts a timer, and the output condition goes back to its original state
before the timer runs out, then the timer will be aborted and the
corresponding digital output will not change state. For example, in the
diagram below, parameter 845 [Dig Out1 Sel] is set to 14 “CurrentLimit”.
CR1 On Delay = 2 Seconds
CR1 On Delay = 2 Seconds
0 5 10
0 5 10
Relay Activates
Current Limit Occurs
Relay Does Not Activate
Cyclic Current Limit
(every other second)