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| 14 | <HR> |
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| 15 | <H2><A NAME="installref"></A> <A NAME="s3">3. Attaching Your Printer</A></H2> |
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| 16 | |
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| 17 | <P>When installing a printer, |
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| 18 | the first step should be to make sure that the printer is actually |
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| 19 | working independently of the software. |
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| 20 | The following section outlines some simple diagnostics that you |
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| 21 | can use to check printer connectivity. |
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| 22 | <H2><A NAME="networkprinter"></A> <A NAME="ss3.1">3.1 Network Printers</A> |
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| 23 | </H2> |
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| 24 | |
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| 25 | <P>The most flexible and highest throughput printer interface is |
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| 26 | via a network (TCP/IP) connection. |
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| 27 | Most high performance printers have a built in network interface, |
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| 28 | or you can attach them to a |
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| 29 | <EM>printer server</EM> |
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| 30 | box which provides a network interface. |
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| 31 | Network print boxes can be obtained from |
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| 32 | Hewlett Packard |
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| 33 | ( |
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| 34 | <A HREF="http://www.hp.com">http://www.hp.com</A>), |
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| 35 | Lantronix's |
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| 36 | ( |
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| 37 | <A HREF="http://www.lantronix.com">http://www.lantronix.com</A>), |
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| 38 | and Rose Electronics |
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| 39 | ( |
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| 40 | <A HREF="http://www.rosel.com">http://www.rosel.com</A>). |
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| 41 | <P>The network interface usually supports multiple network printing protocols. |
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| 42 | The most common are the LPD (RFC1179), Socket API, APPsocket, SMB, |
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| 43 | and Novell Netware interfaces. |
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| 44 | LPRng directly supports the LPD (RFC1179) and Socket API interfaces, |
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| 45 | and you can use the |
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| 46 | <CODE>smbclient</CODE> program from the |
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| 47 | <A HREF="LPRng-HOWTO-5.html#smb">Samba Software Package</A> for the SMB interface. |
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| 48 | There are no plans to support the Novell Netware interface, |
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| 49 | given the wide range of alternatives. |
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| 50 | <H3>Socket API</H3> |
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| 51 | |
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| 52 | <P>The most powerful network connection is via the the |
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| 53 | Socket API. |
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| 54 | The most common Socket API, |
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| 55 | and a <I>de facto</I> standard, |
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| 56 | is the one used by Hewlett Packard on their JetDirect cards, |
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| 57 | which allows a TCP/IP connection to port 9100. |
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| 58 | This is a TCP/IP port on the printer that provides |
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| 59 | a direct connection to the print engine, |
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| 60 | similar to a serial or parallel port. |
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| 61 | This connection is usually full duplex and provides error messages |
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| 62 | and status information during printing. |
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| 63 | <P>The Socket API is extremely simple. |
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| 64 | <OL> |
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| 65 | <LI>The user establishes a connection to port 9100. |
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| 66 | This connection may be refused if the printer is busy |
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| 67 | printing a job.</LI> |
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| 68 | <LI>Once the connection has been established, |
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| 69 | the print job is sent over the connection. |
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| 70 | During this transfer, |
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| 71 | error messages may be returned over the data link.</LI> |
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| 72 | <LI>After sending all the data, |
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| 73 | the sender should do a |
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| 74 | <I>half-close</I> of the connection. |
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| 75 | This tells the printer that no more data will be sent.</LI> |
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| 76 | <LI>After finishing printing the job, |
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| 77 | the printer will close the connection.</LI> |
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| 78 | </OL> |
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| 79 | <P>You can use the |
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| 80 | <A HREF="http://www.l0pht.com/~weld/netcat/">netcat</A> |
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| 81 | utility by Hobbit <CODE><Hobbit@avian.org></CODE> |
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| 82 | to test that this interface is available and working. |
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| 83 | If <I>ellipse.ps</I> is a test file, then: |
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| 84 | The simplest and easiest way to print a file to a network printer appears |
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| 85 | <BLOCKQUOTE><CODE> |
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| 86 | <PRE> |
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| 87 | nc printer.ip.addr 9100 < file |
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| 88 | Example: |
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| 89 | nc 10.0.0.25 9100 < ellipse.ps |
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| 90 | </PRE> |
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| 91 | </CODE></BLOCKQUOTE> |
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| 92 | <H3>LPD (RFC 1179) Protocol</H3> |
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| 93 | |
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| 94 | <P>The second most common network print protocol is the |
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| 95 | RFC1179 TCP/IP protocol. |
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| 96 | This is described in detail in later sections of this document, |
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| 97 | but basically consists of a |
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| 98 | simple set of command and responses. |
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| 99 | <OL> |
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| 100 | <LI>A connection is made to TCP/IP port 515 on the printer. |
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| 101 | As for the Socket API, |
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| 102 | this connection may fail if the printer is busy printing |
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| 103 | another job or has another network connection open.</LI> |
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| 104 | <LI>Once the connection has been established, |
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| 105 | a print request command is sent to the printer, |
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| 106 | and if printing is allowed |
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| 107 | an acknowledgment will be received.</LI> |
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| 108 | <LI>The files comprising the print job are sent to the printer.</LI> |
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| 109 | <LI>The connection to the printer is closed.</LI> |
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| 110 | </OL> |
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| 111 | <P>During the job transfer no error information is returned, |
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| 112 | or other status information. |
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| 113 | This must be obtained by reconnecting to the printer and sending |
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| 114 | a print status request. |
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| 115 | This is a major weakness of the RFC1179 protocol. |
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| 116 | <P>When the LPRng software package has been installed, |
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| 117 | it is easy to check printing by using a command of the form: |
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| 118 | <BLOCKQUOTE><CODE> |
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| 119 | <PRE> |
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| 120 | lpr -Plp@ipaddr -Dnetwork file |
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| 121 | Example: |
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| 122 | lpr -Plp@10.0.0.25 -Dnetwork ellipse.ps |
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| 123 | </PRE> |
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| 124 | </CODE></BLOCKQUOTE> |
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| 125 | <P>The <CODE>-Plp@ipaddr</CODE> option will cause the <CODE>lpr</CODE> program to make a direct |
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| 126 | connection to port 515 and send the print file using the RFC1179 |
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| 127 | protocol. |
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| 128 | The <CODE>-Dnetwork</CODE> debugging option will cause detailed network status to be |
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| 129 | displayed during this process. |
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| 130 | <P>In addition to the <CODE>lpr</CODE> program, |
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| 131 | the Perl <CODE>cheap_lpr</CODE> program can be used. |
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| 132 | This and other test programs are in the LPRng Distribution <CODE>UTILS</CODE> directory. |
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| 133 | <H3><A NAME="appsocket"></A> APPsocket</H3> |
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| 134 | |
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| 135 | <P>The APPsocket interface is supported by Tektronix and some other printer |
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| 136 | vendors. |
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| 137 | It is similar to the Socket API, |
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| 138 | with a couple of minor differences. |
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| 139 | <OL> |
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| 140 | <LI>The printer has two ports for network connections: |
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| 141 | TCP port 9100 for TCP/IP stream connections and UDP port 9101 for UDP |
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| 142 | packet connections.</LI> |
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| 143 | <LI>When a 0 length UDP packet or a UDP packet containing only <CODE>CR/LF</CODE> |
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| 144 | is sent to UDP port 9101, the printer will return a packet to the sender |
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| 145 | containing print status information. |
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| 146 | This information indicates the printers current status (busy, idle, printing) |
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| 147 | and any error conditions.</LI> |
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| 148 | <LI>To send a job to the printer, |
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| 149 | a connection to port 9100 is made. |
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| 150 | This connection will be refused while the printer is busy or has a connection |
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| 151 | to another host.</LI> |
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| 152 | <LI>When the TCP connection is established, |
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| 153 | the job can be sent over the TCP stream. |
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| 154 | When all of the job has been transferred, |
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| 155 | the connection should be <I>shutdown</I> for sending data by the sender, |
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| 156 | but remain open to receive error messages or other information.</LI> |
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| 157 | <LI>An end or job indication in the data stream will also act to terminate |
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| 158 | the connection. |
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| 159 | This means that if the PostScript CTRL-D (end of job) character is sent in |
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| 160 | a job, then the connection will be terminated.</LI> |
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| 161 | <LI>Once all the data has been received and the job has finished printing, |
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| 162 | the connection will be terminated by the printer.</LI> |
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| 163 | </OL> |
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| 164 | <P>The LPRng IFHP filter program has support for the APPsocket interface. |
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| 165 | Also, |
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| 166 | there are Perl or other programs which can communicate with the printer. |
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| 167 | See |
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| 168 | <A HREF="LPRng-HOWTO-5.html#P450">Tektronix P450 and Family</A> for details. |
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| 169 | <H2><A NAME="secnetwork"></A> <A NAME="ss3.2">3.2 Network Print Server Boxes</A> |
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| 170 | </H2> |
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| 171 | |
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| 172 | <P>A ``network print server'' is usually a box |
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| 173 | (external model) or card in a printer (internal model) |
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| 174 | which has a network connection to a TCP network and |
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| 175 | software to implement a LPD print server. |
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| 176 | If it is an external model, |
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| 177 | The parallel or serial port of |
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| 178 | the printer is connected to the box, |
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| 179 | and the print server may support multiple printers. |
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| 180 | If it is an internal model, |
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| 181 | the server is usually nothing more than a Network Interface Controller |
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| 182 | and a ROM containing software that the microprocessor in the printer |
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| 183 | uses. |
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| 184 | <P>The print server may support multiple printing protocols, |
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| 185 | such as |
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| 186 | <A HREF="LPRng-HOWTO-6.html#rfc1179">RFC1179</A> |
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| 187 | (TCP/IP printing using the LPD print protocol), |
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| 188 | Novell Printer Protocols, |
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| 189 | SMB print protocols, |
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| 190 | and AppleTalk protocols. |
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| 191 | One of the observed problems with Network Print servers is that while they |
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| 192 | can usually support one protocol and one user at a time quite well, |
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| 193 | when you try to use multiple protocols and/or multiple users try to transfer |
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| 194 | print jobs to the printer, the printer may behave in a very odd manner. |
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| 195 | Usually this results in a printer failing to finish a job currently being |
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| 196 | printed, |
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| 197 | and unable to accept new jobs. |
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| 198 | <P>Several of the newer models of print servers have |
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| 199 | Simple Network Management Protocol (SNMP) agents built into them, |
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| 200 | and can provide detailed information about their internal functions. |
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| 201 | By using a SNMP manager such as SunNetmanage or HP-Openview, |
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| 202 | you can monitor your network printers activities. |
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| 203 | <P>I recommend that you use only a single protocol to send jobs to the printer. |
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| 204 | If you can, I also recommend that you use a print spooler and have only |
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| 205 | a single host system send a job to the printer. |
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| 206 | <P>My best advice on connecting to network printers is not to use the |
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| 207 | the built-in LPD server, |
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| 208 | but to use the direct TCP/IP connection to the print engine. |
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| 209 | Usually this is done to particular TCP/IP port on the printer. |
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| 210 | For the HP JetDirect and other HP products, this is usually |
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| 211 | TCP port 9100. |
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| 212 | <P>Once you have the direct connection, |
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| 213 | you can now use various filters to preprocess the print job, |
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| 214 | insert PJL and PCL commands, |
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| 215 | or convert text to PostScript or PCL for better print quality. |
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| 216 | <P> |
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| 217 | <H2><A NAME="ss3.3">3.3 Parallel Printers</A> |
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| 218 | </H2> |
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| 219 | |
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| 220 | <P>In most UNIX systems the printer port has the name |
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| 221 | <CODE>/dev/lpt</CODE>, |
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| 222 | <CODE>/dev/prn</CODE>, |
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| 223 | or something similar. |
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| 224 | On most systems the |
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| 225 | <CODE>dmesg</CODE> utility will print a list of IO devices found |
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| 226 | during system configuration. |
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| 227 | Use the following commands to get the information and scan |
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| 228 | for the device. |
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| 229 | You should also make sure that the printer device is |
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| 230 | available. |
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| 231 | <BLOCKQUOTE><CODE> |
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| 232 | <PRE> |
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| 233 | dmesg >/tmp/a |
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| 234 | grep lp /tmp/a |
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| 235 | ls /dev/lp* |
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| 236 | </PRE> |
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| 237 | </CODE></BLOCKQUOTE> |
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| 238 | <P> |
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| 239 | <P>Gordon Haverland |
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| 240 | <CODE><haverlan@agric.gov.ab.ca</CODE>> supplied this little script, |
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| 241 | that will assist with this: |
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| 242 | <BLOCKQUOTE><CODE> |
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| 243 | <PRE> |
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| 244 | #!/bin/sh |
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| 245 | #set -v -x # uncomment for debugging |
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| 246 | PATH=/bin:/usr/bin |
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| 247 | printer= |
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| 248 | for printer in /dev/lp* ; |
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| 249 | do |
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| 250 | echo PRINTER TEST to $printer 1>&2 |
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| 251 | for i in 1 2 3 4 5 6 7 8 9; |
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| 252 | do |
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| 253 | echo PRINTER $printer $i > $printer; |
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| 254 | done |
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| 255 | echo -e \\r\\f > $printer |
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| 256 | done |
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| 257 | exit 0; |
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| 258 | </PRE> |
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| 259 | </CODE></BLOCKQUOTE> |
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| 260 | <P>If your printer is connected to the device name you provided, |
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| 261 | then you should get a page of something out. If the output |
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| 262 | suffers from the ``staircase'' effect, you will see the numbers |
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| 263 | ``marching'' across the page, otherwise the numbers will all be in |
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| 264 | a single column. |
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| 265 | <H2><A NAME="secserial"></A> <A NAME="ss3.4">3.4 Serial Printers</A> |
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| 266 | </H2> |
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| 267 | |
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| 268 | <P>If your printer is attached by a serial line, |
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| 269 | then you may need to set the serial line characteristics before sending |
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| 270 | the job to the printer. |
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| 271 | Here are a set of guidelines to following when attaching a serial port printer |
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| 272 | to a serial line. |
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| 273 | <P>1. Check to make sure that the line is not enabled for login. |
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| 274 | Logins are usually managed by the |
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| 275 | <CODE>getty</CODE> (BSD) |
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| 276 | or |
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| 277 | <CODE>ttymon</CODE> (Solaris, SystemV). |
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| 278 | Check your system documentation and make sure that these daemons are not |
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| 279 | managing the serial line. |
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| 280 | <P>2. Check the permissions and ownership of the serial line. |
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| 281 | For the most easy testing, |
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| 282 | set the permissions to 0666 (everybody can open for reading and writing). |
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| 283 | After you have made sure that you can send jobs to the printer, |
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| 284 | you might want to change the ownership of the serial line to the LPD server |
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| 285 | and change the permissions to 0600. |
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| 286 | <P>3. Make sure that you can print a test file on the printer via the |
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| 287 | serial port. |
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| 288 | This may require setting the line characteristics and then sending |
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| 289 | a file to the printer. |
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| 290 | You should try to use 8 bit, no parity, with hardware flow control |
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| 291 | and no special character interpretation, |
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| 292 | and definitely no LF to CR/LF translation. |
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| 293 | The problem is that different versions of UNIX systems have different |
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| 294 | sets of stty(1) commands to do this. |
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| 295 | The following simple test script can help in this. |
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| 296 | <BLOCKQUOTE><CODE> |
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| 297 | <PRE> |
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| 298 | #!/bin/sh |
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| 299 | # 9600, no echo, no CR |
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| 300 | FLAGS= 9600 -raw -parenb cs8 crtscts |
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| 301 | DEV= /dev/tty01 |
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| 302 | (stty $FLAGS; stty 1>&2; cat $1 ) <$DEV >$DEV |
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| 303 | </PRE> |
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| 304 | </CODE></BLOCKQUOTE> |
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| 305 | <P>This shows using stty to set the flags, |
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| 306 | then to print the current settings, and then using |
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| 307 | cat a file to the output. |
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| 308 | If you attach a dumb terminal to the serial port, |
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| 309 | you can even use this script to ensure that input from the device |
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| 310 | is echoed to the output with the correct speed, parity, |
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| 311 | etc. |
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| 312 | <P>Experience has shown that serially connected printers are the least |
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| 313 | reliable and lowest speed. |
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| 314 | Where possible, |
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| 315 | it is strongly recommended that they be attached to a <I>network print box</I> |
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| 316 | which will provide a |
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| 317 | Socket API interface and handle the low level network to serial port protocol |
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| 318 | conversions. |
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| 319 | <HR> |
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| 320 | <A HREF="LPRng-HOWTO-4.html">Next</A> |
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| 321 | <A HREF="LPRng-HOWTO-2.html">Previous</A> |
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