Sony RM-E300 Operating Instructions Manual page 17

Note on the COMMAND MODE selector
When the infrared beam detector is equipped with the player and
the recorder
1 Set the COMMAND MODE selector on the player to a
different position from that on the recorder.
2 Set the COMMAND MODE select switch on this unit to the
same position as that on the recorder.
3 If the COMMAND MODE on the recorder and the player are
the same and they are not equipped with the selector, cover
the detector of the player with paper or equivalent.
Others
* When the connecting cable is connected to the CONTROL L or
CONTROL §S connector on this unit, the infrared beam cannot
be emitted.
+ Even if this unit is equipped with tape transport functions, if the
recorder is not equipped with some of their functions, it cannot
be operated with this unit.
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