Lantronix ETS Reference Manual - 7.2   Lpr Printing

LPR Printing

TCP/IP Host Setup

7-2

RTEL 

Lantronix supplies RTEL host software, which requires installation and 

configuration on the host but provides more functionality than remote-LPR. It 

allows the host’s lp or lpr printing system to transparently use the ETS print 

devices, and also allows the creation of named pipe devices on the host that 

map to the ETS’s ports. 

The RTEL backend filter interfaces with the host-based spooling system. It 

receives data from the spooling system and sends the data to the ETS. The 

advantages of the backend filter are that the banner page is printed at the front 

of a job, multiple copies can be printed, and simple reformatting such as 

to  conversion and tab expansion can be performed. However, the 

backend filter does not support any complicated output filtering or 

conversions.

The RTEL Pipe Daemon process (RTELPD) uses a UNIX named pipe as its 

interface to the host. This allows any host-supplied or user-supplied backend 

filter to be used for printing. Any data that is sent into the pipe is simply moved 

to the ETS. However, the data flow is one-way from the host system to the ETS 

and this approach does require one RTELPD daemon process for each print 

queue configured.

TCP Socket Connects The ETS supports direct TCP connections to its ports. These connections 

provide 8-bit clean full-duplex data communication, but they do require that 

the user provide his or her own software. The RTEL software includes an 

example program showing how to form these connections. 

The TCP Socket interface does not support queueing. If the resource is busy 

when a connection attempt is made, the connection will be rejected.

7.2   LPR Printing

There are several important things to note about the LPR printing method:

◆

Windows for Workgroups, Windows 95, Windows 98, and Windows 200 do not support LPR 

directly; however, Lantronix has provided a peer-to-peer printing solution on the distribution CD-

ROM. 

◆

Because of the way the LPR protocol is typically implemented on the host, the processing options and 

banner page are sent after the job data itself. The ETS will print a banner page at the end of a job, and 

cannot support most of the LPR options. If it is necessary to have the banner page at the beginning of 

the printout, install and use the RTEL software. If banners are not needed, they can be disabled.

◆

The ETS cannot print multiple copies of the print job when using the “-#n” lpr option.

◆

If two print queues on the host refer to two services on the same ETS, they must use separate spooling 

directories. 

◆

No special purpose input or output filters can be used when printing via LPR. If this functionality is 

necessary, use the named pipe interface program in the RTEL print queue configuration software.