Recovery Procedure for POT/NOT Limit Switch Activation on B5 Unitronics Servo Motor

The B5 servo motor is equipped with two limit switches: a positive limit switch (POT) and a negative limit switch (NOT). These switches serve as safety mechanisms to prevent the servo from moving beyond its defined operational range. When the motor reaches either limit switch, it automatically stops and sets a corresponding status bit in its control registers. This protective feature ensures the servo doesn't attempt to move beyond its mechanical limits, which could potentially damage the system.

To resume normal operation after a limit switch activation, the control system must follow a specific sequence of commands to safely move the servo away from the limit position and re-enable normal operation. The recovery process involves reading status registers, sending specific position commands, and resetting target positions using the SDO protocol.

1) Identify the Activated Limit Switch

• Use SDO Upload function to read address H60FD (hex), sub-index = 0 in the length of 4 bytes.
• The first bit indicates NOT activation.
• The second bit indicates POT activation.

2) Send Recovery Position Command

• Use SDO Download function to address H607A (hex) index 0, sub-index 4
• For POT activation: Send value -88684080.
• For NOT activation: Send value 88684080.
• This will put the servo into Ready mode.

3) Move Away from Limit Switch

• Once the limit switch is deactivated, use MC jog function to move the servo away from the limit position.
• The servo will now respond to movement commands.

4) Reset Target Position

• After clearing the switch condition, reset the target position.
• Send SDO Download to address H607A (hex), sub-index 0, num of bytes = 4.
• Set buffer value to 0.
• This reactivates the POT/NOT functionality.

This procedure will restore normal operation of the servo motor after encountering a limit switch condition.