Dear Forum ,
Since some time I am testing the application , published in october 2013 to write / append data to a FTP server.( In my case a NAS-device )
I used the project from the website and did some minor modifications that are doing the filename and data based on time of day.
The write request is send every minute.
I see that after some hours the data is no longer written to the file and the responses received from the server are different.
If I power off the PLC , writing has started again . I tried changing from the NAS to Filezilla on a PC , after it wend wrong , but it also does not write .

Filezilla log :
(000001)24/04/2014 12:19:53 - (not logged in) (10.0.0.11)> Connected, sending welcome message...
(000001)24/04/2014 12:19:53 - (not logged in) (10.0.0.11)> 220 FileZilla Server version 0.9.43 beta
(000001)24/04/2014 12:19:53 - (not logged in) (10.0.0.11)> USER admin
(000001)24/04/2014 12:19:53 - (not logged in) (10.0.0.11)> 331 Password required for admin
(000001)24/04/2014 12:19:53 - (not logged in) (10.0.0.11)> PASS admin
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> 230 Logged on
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> TYPE I
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> 200 Type set to I
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> PASV
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> 227 Entering Passive Mode (10,0,0,9,203,149)
(000001)24/04/2014 12:19:53 - admin (10.0.0.11)> APPE DATA/2014/2014_04_24.DAT
(000001)24/04/2014 12:20:03 - admin (10.0.0.11)> 425 Can't open data connection for transfer of ""
(000001)24/04/2014 12:20:05 - admin (10.0.0.11)> disconnected.

and what the NAS-people discovered during a teamviewer session

We found that PLC did not follow the ftp process , can you check that with PLC manual ? In this case, FTP server tell client passive mode is in port (217,60), that is port 55612.

Then after client asked APPEND to the data file, it should try to connect to port 55612, but it didn't.

Is there anyone who has tested the FTP project ?
What did you discovered ?

Thanks in advance.

In this mode, the FTP client opens a random port (>1023) and sends it and its own

IP address to the FTP server using a special command (PORT or EPRT). As a

standard, it is sent to port 21 of the FTP server (it must be open at the server or

forwarded, otherwise no communication will be established). When data transfer is

requested, the FTP server now initiates a TCP connection to the transferred IP

address and the port from FTP server port 20.

The active mode is used when the FTP server is located behind a firewall, since

the data connection is initiated from the FTP server outwards, hence, not blocked

by the firewall; i.e. the FTP server acts actively.

In this mode, the FTP client sends a PASV or EPASV command to port 21 of the

FTP server, which prompts it to open a random port and transferring it to the FTP

client with its IP address. For the data transfer, the FTP client now initiates a TCP

connection to the IP address sent by the FTP server and the port.

The passive mode is used when the FTP client is located behind the firewall since

the data connection is initiated from the FTP client outwards and the firewall

normally does not block any packages. The FTP server hence reacts passively.

Hi ,
Still testing with the NAS and trying to solve it with the NAS-people.

I found that it all works well if the PLC and the NAR are isolated from the rest of the LAN neighborhood. If it has failed , I only have to reboot the NAS to restart.

So , It looks as the NAS is the real problem.
It becomes unstable if other device are communicating over the same network.

koenb

Hi ,
Still testing with the NAS and trying to solve it with the NAS-people.

I found that it all works well if the PLC and the NAR are isolated from the rest of the LAN neighborhood. If it has failed , I only have to reboot the NAS to restart.

So , It looks as the NAS is the real problem.
It becomes unstable if other device are communicating over the same network.

special thanks to Owei.

koenb

 Hi,

i am also facing Timeout error using active mode and port active mode 2001 . please tell me how to resolved.?