Speed Reference - Allen-Bradley PowerFlex 70 Reference Manual

Speed Reference

Speed Reference
Operation
The output frequency of the drive is controlled, in part, by the speed command
or speed reference given to it. This reference can come from a variety of sources
including:
• HIM (local or remote)
• Analog Input
• Preset Speed Parameter
• Jog Speed Parameter
• Communications Adapter
• Process PI Loop
• Digital Input MOP
Selection
Binary Logic
Some references can be selected by binary logic, through digital inputs to the
terminal block or bit manipulation of the Logic Command Word in a
communications adapter. These sources are used when the drive is in "Auto"
mode. The default reference is from the source selected in [Speed Ref A Sel],
parameter 90. This parameter can be set to any one of the 22 choices. If the
binary logic selection is zero, this will be the active speed reference.
Auto/Manual
Many applications require a "manual mode" where adjustments can be made and
setup can be done by taking local control of the drive speed. Typically, these
adjustments would be made via a "local" HIM mounted on the drive. When all
setup is complete, control of the drive frequency command is turned over to
automatic control from a remote source such as a PLC, analog input etc.
The source of the speed reference is switched to one of two "manual" sources
when the drive is put into manual mode:
1. Local HIM
2. Analog Input to terminal block
If the selection is the HIM, then the digital or analog speed control on the HIM
provides the reference.
If the switch to manual mode was made via a digital input, (parameters 361-366
set to "18, Auto/Manual") then the source for the reference is defined in [TB
Man Ref Sel], parameter 96. This can be either of the 2 analog inputs or the
digital MOP.
When the drive is returned to automatic mode, the speed reference returns to the
source selected by the binary logic. Also see Auto/Manual on page 36.
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013 167