Printing with TN3270 Plus

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Printing with TN3270 Plus sometimes causes some confusion because there are four different ways to print.


1.Print screen.
2.Printer session
4.Printer passthrough        


The following table summarizes the differences between the printing methods. You can find more detail about each method following the table.






Terminal Types


Host Computers

Print screen




Printer session

3270 Terminal Feature or 5250 Terminal Feature
Print Feature

3270, 5250

IBM zSeries (mainframe)

IBM iSeries (AS/400)


Print Feature


All (LPR is required on the host computer)

Printer passthrough


VT100, VT220, ANSI


Print Screen

"Print Screen" support is just what it sounds like. It lets you print the contents of the current screen. You can print a single screen on a local or network printer. This is a standard feature and works for all terminal types.

If you want to print multiple screens you can turn on TN3270 Plus logging and save screens to a log file. After you have logged all the screens you want to save you can turn logging off and print the log file.

Printer Session

A printer session allows you to send host computer print jobs via to TN3270 Plus to a Windows printer. A printer session looks like a printer to the host computer. Your printer session can print jobs on any local or remote Windows printer.

Printer sessions are supported only by IBM zSeries (mainframe) and iSeries (AS/400) host computers. You cannot create a printer session for a UNIX host computer. You must license the TN3270 Plus Printer Support. You must also have the corresponding terminal feature, so the 3270 Terminal and/or the 5250 Terminal feature is also required.

Printer definitions must be properly configured on the host computer before you can use printer sessions. If you want to use a printer session, you need to get a printer LU name (IBM zSeries) or a printer device name (IBM iSeries) from the network administrator for the host computer.

See Connecting a TN3287 Printer Session and Connecting a 5250 Printer Session for more information.


SDI LPD is a Line Printer Daemon and it also allows you to send host computer print jobs to a Windows printer. SDI LPD is a separate executable program (sdilpd.exe). While it is running it awaits print jobs from a Line Print Requester (LPR). You can find out more about how SDI LPD works in the . You must license the TN3270 Plus Print feature to enable SDI LPD.

Since Printer Sessions and SDI LPD accomplish the same goal, how do you choose which you need to use? The biggest advantage of printing with SDI LPD is that almost all host computers support LPR and can send print jobs to SDI LPD. This includes UNIX systems which do not support printer sessions. The biggest disadvantage is that the host computer must send the print job to the IP address of the PC running SDI LPD. This becomes a problem if you connect to a host computer via an Internet dial-up connection because dial-up connections are assigned a new IP address every time they connect. This means the LPR commands on the host computer must be changed to send print jobs to your new IP address each time you make a new dial-up connection to the Internet. Printer sessions use the LU name or Device name to identify the printer session and that name is associated with the IP address when the connection is made to the host computer. So, it does not matter if your IP address changes each time you connect to the Internet.

Printer Passthrough

Printer passthrough is a UNIX feature that sends data to a terminal printer. UNIX initiates printer passthrough by sending a control sequence to the terminal to start printer passthrough. Host data is sent to the printer until UNIX sends a control sequence to turn printer passthrough off. TN3270 Plus supports printer passthrough and sends the printer passthrough data to the Windows printer defined in the printer pane of the session setup dialog box.


TN3270 Plus is continually being improved. To learn more about the latest enhancements, please review our Version History web page.