5-18 Syntax and Parameters
MX2 Reference Guide Revision A MX2A137REFGD
T
Transmit File(s)
This option specifies that files are to be sent. For Xmodem protocol, this
is the default; that is, typing XFER MYFILE on the command line
would send the file MYFILE.
For Zmodem protocol, transmit is the default if you specify a file on the
command line. So, for example, the command XFER /Z MYFILE is
equivalent to the command XFER /Z /T MYFILE.
The T option is most useful if the XFER_ARGS environment variable
includes the R command but you want to send a file.
Note: The last transfer option, R or T, on the command line controls
whether to transmit or receive for the session.
W
Window Size (Zmodem only)
This option controls the use of windowing with Zmodem protocol. By
default, Zmodem is a streaming protocol, and windowing is disabled.
“Streaming” refers to the method by which Zmodem transfers data. In
streaming mode, the sender forms 1K data packets and sends one packet
after another in a continuous stream. The sender does not wait, and does
not expect, to get acknowledgments from the receiver for any of the
packets it sends. Instead, the sender assumes the file transfer is going
normally unless it gets an error indication from the receiver.
This works fine in robust, error-free environments. But the receiver can
get lost or disconnected without the sender realizing it. Windowing
provides a way in noisy environments to give some level of packet
acknowledgment to Zmodem protocol. With windowing, the sender will
send up to the number of bytes specified by the size of the window and
then stop transmitting data until the receiver acknowledges that it has
received all of the packets that have been sent. The sender then sends
more packets, up to the size of the window, and so on.
Waiting for acknowledgments slows down transfer speeds, but XFER
allows a dynamic compromise between speed and robustness. XFER lets
you specify the window size with any value from 0 to 65535. Use W0
for streaming mode. For a 1K window, use W1024. Values below 1024
are used exactly as specified and should be the size of the transmitted
packets. Values above 1024 should be multiples of 1024 (1024, 2048,
