Automatic history sending corrupts command priority switching

Context: RoboteQ SDC2130 dual controller. Initially setup in default mode with serial then RC priority. The RC input initially works fine to control the robot. Once a serial command is sent to start automatically sending position updates (history # nn), the RC control never works thereafter. This seems to contradict the documented behavior.

Further investigation seems to indicate the cause is related to other unanticipated communication activities. Pure history streaming by itself did not inhibit RC action.

Problem traced to unintended setting of PID parameters (via serial port) by master computer that were incompatible with RC mode.

How was the computer setting the PID values? I am quite curious...

Master computer sent a series of serial commands of the form:
^KP 1 10\r
and similarly for KI, KD and other parameters.

It also set values for several other modes and options.