FTP files from a PLC


#1

I have many PLCs (Programmable Logic Controller) throughout the world that are used in an industrial plant to gather historical data (temps, pressure, quantity, ON/OFF state of equipment etc). This data is then sent as a .csv text file via FTP to a server when the local user pushes a button on the control panel. I created a user account for the PLC to send files to. I can use the FTP client within WinXP to access the new user account. My problem is I can’t get my PLC to send its file to the DreamHost servers. I can set up a simple FTP server on a local PC and the PLC will send its file just fine.

Is there some simple thing I missed that is preventing the FTP server from receiving the file?


#2

There shouldn’t be any extra hoops to go through.

Does the PLC assume it’s anonymous FTP, or can you specify the username and password?
Does the PLC have a session log?
Are you sure that the user account here is set up for FTP access? Sometimes it’s limited to SFTP only.
Can PCs at these other plants FTP to the server here?


#3

I can specify username and password.
The PLC does not have a session log.
User account is setup for FTP access.
I can connect to the various user accounts using a PC but I can not send a file. If I use copy and paste to send the file, I can copy a file but the paste function is greyed out. Its behaving like the user accounts are setup for read only.


#4

When you say “user accounts,” that implies more than one. Typical FTP is single-user only, meaning that multiple FTP usernames can’t log into another FTP user’s home directory. PLC1 can only FTP as PLC1 and connect to /home/PLC1. PLC2 won’t be able to FTP as PLC2 and upload to PLC1’s directory. And if you created a user like CENTRAL, nobody but CENTRAL can upload to /home/CENTRAL.

You said you were able to use WinXP’s FTP program to access the user account. Could you upload as well? If so, then you should be able to use WinXP at the remote sites in the exact same way.


#5

All the PLCs use the same user account. Each PLC will send a different filename. When I use WinXP to access the same account I can not upload a file. If I use WinXP to connect to a different account, I have the same problem… can’t upload a file.


#6

OK, I’m a dumb guy!! I found the problem. It seems a while back I installed a new router and forgot that the new router had a new gateway IP address. My PLC was looking to the old gateway address and could not find the new router and therefore could not get to the DH servers.