Rockwell Automation WebPak 3000 DC Drive Application Workbook Version 1.1 - Manual (Page 66)

11-4 WebPak 3000 DC Drive Application Workbook, Version 1.1
11.2 The Position PI Input
The input to the position PI block is the rate-limited value of POSITION REFERENCE
(P.240). The input to the RATELIM block is P.240, the output is POS RAMP OUTPUT
(P.237).
þ
To configure the position PI block input:
▲
Set POSITION REFERENCE (P.240) to specify the dancer position reference in
counts. The value in P.240 defines the dancer loop position during steady
state operation, which would normally be the midpoint of the dancer storage
(typically 2048 counts).
▲
Set POS RAMP TIME (P.233) to specify the reference rate of change to minimize
position loop transients during the adjustment of P.240.
▲
The analog position feedback signal must be connected to terminals 52(+)
and 53(-) on the I/O Expansion board.
The standard type of PI block feedback is an analog signal proportional to
dancer position; therefore, it is assumed that the dancer position transducer is
either a potentiometer or some other type of linear or rotary transducer whose
output has been converted to an analog signal and conditioned to provide a 0
to 10 volt
DC signal linear from 0 to maximum position (free storage).
▲
Set TENSION / DANCER GAIN (P.417) to adjust the gain of the analog input signal.
▲
If necessary, set TENSION / DANCER ZERO (P.416) to adjust the zero point of the
analog input signal.
TENSION / DANCER FDBK (P.493) is the scaled value of the analog signal used for
position feedback to the PI block. The position feedback signal is conditioned by a
SCALE block and a LEAD / LAG block which is set to approximately cancel the lag
attributable to the speed loop bandwidth.
The LEAD / LAG block values are set using the procedures detailed in section 11.1.
þ
To set up the SCALE block:
▲
Set TENSION FDBK MIN (P.852) to set the lower limit.
▲
Set TENSION FDBK MAX (P.851) to set the upper limit.
Range: -4095 to 4095 COUNTS (4095 = FREE STORAGE ) P.240 = COUNTS
Range: 0.1 to 60.0 SECONDS P.233 = SECONDS
Range: 0.750 to 2.250 P.417 =
Range: -3000 to 3000 COUNTS P.416 = COUNTS
Range: -4095 to 4095 COUNTS P.852 = COUNTS
Range: -4095 to 4095 COUNTS P.851 = COUNTS