Receiving a Zero Byte File in 3780 BSC RJE Emulation

Issue:  A user is receiving a zero byte count on his last file.  He wants to know why.

Answer:  Sometimes you may receive a file with nothing in it.  A so called "zero byte" file.  There are two situations where a zero byte file is possible.  The first one is when we open the next sequential file and then receive an End of Transmission instead of another file.  When that happens, the FastSync 3780 program will close the empty file and delete it.

The second situation is when a zero byte file is received.  (The data consists of STX ETX).  Since the empty file usually signifies that all files have been transmitted, the existence of the empty file is useful information for some customers (it indicates a complete session.)  The FastSync 3780 program does not delete the file when this happens.

Issue (same as above, but stated differently):  Can you please help me?  I would like to know if it is normal that every  time I connect to WalMart, I always get 2 files, one with data and the other blank.

Answer:  If Wal-Mart has data to send, they send all batches (files) they have in your mailbox.  It appears that their host system assumes that there always another file in your mailbox.  When they have transmitted the last file, they have already started the 3780 process for the next file.  As a result, they always end with an empty file.

When they do not have any files, they send a standard "No Batches for Transmission" file and hang-up.

FastSync assumes that an empty file is significant, so it does not delete empty files In fact, the empty file is your assurance that you have received all batches Wal-Mart had for you.  If you receive a single data file without an empty file, it could mean that there are more files in your mailbox.


If you're receiving a zero byte file, you could try using .IF LASTFILESIZE = 0 in your command file and then using .ERASE for any files that have zero length.  Or, add command line code such as: 

  1. 10.RCVE,INFILE
  2. 15.IF LASTFILESIZE = 0 THEN .GOTO 30
  3. 20.PROMPT, SOME FILES MIGHT NOT HAVE BEEN RECEIVED!
  4. 25.GOTO 99
  5. 30.PROMPT, ALL FILES WERE RECEIVED
  6. 99 .EXIT

   Note:  Each command starts with a dot ( . ).  In the above example, the ".", is preceded by an optional line number( except the 5th line which requires a referenced number).

 Click for a list of program Commands along with a quick overview

Click for an overview on how to functionally use FastSync3780 commands

Click for detailed use of commands

The most popular 3780 package including modem: SyncPack2000e (no sync card required)

Some of the manufacturers using FastSync 3780 Software

Banks/Credit Unions using FastSync 3780 Software