Bumpless Transfer in PIDs means that switiching between auto and manual modes of PID without upsetting the output value. In PLC it is done by loading the PID output register value in a spare register while in Auto mode. Once switched to Manual, the value in register is loaded in the PID output register. This way the output doesnt get disturbed.
In DCS we have to simply allow the option of “SP Tracking PV”.