SCN 4049 created the Selective Closed Loop feature. It describes how the feature works.

Two bugs were found in the feature, both related to Coil Tail In.

1. The original change included the ability to switch from Closed Loop to Open Loop on the fly during a Coil Tail Out. However, the code failed to prevent switching from Open Loop to Closed Loop on the fly, which would only happen on a Tail In. The Tail It causes a jump in the Command signal due to the loop error that accumulates while in Open Loop. A large enough loop error results in a Drive Not Responding Error. The solution was to force the controller to stay in Open Loop until the material stops and the motor is disabled. Switching to Closed Loop only occurs when the material is stationary while enabling the motor.

2. The motor Set-Point was not being set correctly during a Tail In. This resulted in a Slip Test Error because the Selective Closed Loop performs a Slip Test by making sure the loop error does not become excessively large. The incorrect Set-Point was resulting in loop errors large enough to trigger the Slip Test failure.