Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 83)

Rockwell Automation Publication 750-RM002B-EN-P - September 2013 83
Drive Configuration Chapter 1
The drive must be in Run before the PID Enabled status can turn on. The PID
remains disabled when the drive is jogged. The PID is disabled when the drive
begins a ramp to stop, except when it is in Trim mode and the Stop mode bit in
P1065 [PID Cfg] is enabled.
When a digital input is configured as “PI Enable,” the PID Enable bit of P1066
[PID Control] must be turned On for the PID loop to become enabled. If a
digital input is not configured as “PI Enable” and the PID Enable bit in [PID
Control] is turned On, then the PID loop can become enabled. If the PID Enable
bit of [PID Control] is left continuously, then the PID can become enabled as
soon as the drive goes into Run. If analog input signal loss is detected, the PID
loop is disabled.
PID Hold
The Process PID Controller has the option to hold the integrator at the current
value so if some part of the process is in limit the integrator maintains the present
value to avoid windup in the integrator. The logic to hold the integrator at the
current value is shown in the following ladder diagram. There are three
conditions under which Hold turns on.
• If a digital input is configured to provide PID Hold and that digital input
is turned on then the PID integrator stops changing. Note that when a
digital input is configured to provide PID Hold that takes precedence over
the PID control parameter.
• If a digital input is not configured to provide PID Hold and the PID Hold
bit in the PID Control parameter is turned on the PID integrator stops
changing.
• If the current limit or voltage limit is active then the PID is put into Hold.
Running Running
DigInCfg
.PI_Enable
DigInCfg
.PI_Enable
DigIn
.PI_Enable
PI_Control
.PI_Enable
PI_Status
.Enable Signal Loss
DigInCfg
.PI_Enable
PI_Control
.PI_Enable
DigInCfg
.PI_Hold
PI_Status
.PI_Hold
DigIn
.PI_Hold
DigInCfg
.PI_Hold
PI_Control
.PI_Hold
Current Lmt
or Volt Lmt