Below is quoted from my Fanuc manual, kinda vague but should be able to figure out at the machine...... notice reference to the "REMOTE" (RMT) key.
Parameters/settings have already been accomplished (I believe) since he's already able to download/upload through his RS232.
By activating automatic operation during the DNC operation mode
(RMT), it is possible to perform machining (DNC operation) while a
program is being read in via reader/puncher interface, or remote buffer.
Press the REMOTE switch on the machine operator’s panel to set
RMT mode, then press the cycle start switch. The selected file is
executed. For details of the use of the REMOTE switch, refer to the
relevant manual supplied by the machine tool builder.
To use the DNC operation function, it is necessary to set the parameters
related to the reader/punch interface, and remote buffer in advance.
This CNC has a total of three channels of reader/puncher and remote
buffer interfaces. It also has a memory card interface. The input/output
device to be used is specified by setting the channel (interface) connected
to that device in setting parameter I/O CHANNEL.
The specified data, such as a baud rate and the number of stop bits, of an
input/output device connected to a specific channel must be set in
parameters for that channel in advance.