Rockwell Automation Publication 520-UM001G-EN-E - September 2014 199
Velocity StepLogic, Basic Logic and Timer/Counter Functions Appendix D
• Transition to Step 2 when both Logic In 1 and Logic In 2 are true.
The drive senses the level of both Logic In 1 and Logic In 2 and transitions
to Step 2 when both are on.
• Transition to Step 3 when Logic In 2 returns to a false or off state.
Inputs are not required to remain in the “on” condition except under the
logic conditions used for the transition from Step 2 to Step 3.
The step time value and the basic logic may be used together to satisfy machine
conditions. For instance, the step may need to run for a minimum time period
and then use the basic logic to trigger a transition to the next step.
Timer Function
Digital inputs and outputs control the timer function and are configured with
parameters t062...t063, t065...t068 [DigIn TermBlk xx] set to 19 “Timer Start”
and 21 “Reset Timer”.
Digital outputs (relay and opto type) define a preset level and indicate when the
level is reached. Level parameters t077 [Relay Out1 Level], t082[Relay Out2
Level], t070 [Opto Out1 Level] and t073 [Opto Out2 Level] are used to set the
desired time in seconds.
Parameters t076 [Relay Out1 Sel], t081 [Relay Out2 Sel], t069 [Opto Out1 Sel]
and t072 [Opto Out2 Sel] are set to 25 “Timer Out” and causes the output to
change state when the preset level is reached.
Example
• Drive starts up and accelerates to 30 Hz.
• After 30 Hz has been maintained for 20 seconds, a 4-20 mA analog input
becomes the reference signal for speed control.
Time
Logic In 1
Logic In 2
Frequency
Start Step 0 Step 1 Step 2 Step 3
Time
Logic In 1
Logic In 2
Frequency
Start Step 0 Step 1
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