Limit Switch Deadband

by | Oct 1, 2019 | Grid Connect Configuration-Group

The control logic calibrates on the Minimum Limit Switch. After a short delay any time the switch is ON the calibration value from FI4 AX1calibrateLS or FI5 AX2calibrateLS will be written to the Pv register ie. FO101 AX1pv_01_1

The limit switch inherently has dead band as the position to cause the limit switch to be ON when calibration to the position where it releases to OFF requires a few degrees of travel.  This introduces a small error as the Tracking phase begins.

This procedure will correct this without any instrumentation.


Enable Calibrate X18 Calibrate

Once the Minimum Limit Switch is ON,  record the raw counts

ie. X1801 AX1minLS_01_1 becomes TRUE and AX1count_01_1 = 26358

Allow to track so minimum Limit Switch goes OFF.

There should be travel without the Pv changing until the Limit Switch releases.

ie. X1801 AX1minLS_01_1 becomes FALSE and AX1count_01_1 = 27075

This can be recorded in GRIDview trends with these registers.

Overlay the Limit Switch X1801 AX1minLS_01_1 with the counts AX1count_01_1 for the exact count.

Then do this calculation:

27075 – 26358 = 717 counts

717 / 29260 (Pulses per 360.0 deg revolution ie. AX1ppr) = 0.00407

0.00407 * 360.0 = 8.82 degrees deadband  enter into AX1limitSWdb or AX2limitSWdb