About the Digital Sender
The Hewlett-Packard Digital Senders are, in essence, networked scanners. The 8100c, which is out of production, was the second such device that HP made; the current model (as of February 2008) is the 9200c. The 8100c supports scanning to PDF, JPEG, or TIFF files which are then sent as email attachments, faxing, and copying printed documents directly to a JetSend supported printer.
The 8100c appears to be formed — in both a physical, and logical sense — from a SCSI scanner, an automatic document feeder, and a low-end computer with a simple keyboard and four-line LCD output subsystem. The computer has a fixed amount of on-board memory, an EIO interface used to provide network connectivity, a SCSI interface for the scanner, and an IDE hard drive interface.
My 8100c is configured with an HP j3110a/JetDirect 600N 10Base-T EIO card. This card provides the ethernet interface to the scanner. The current firmware load doesn't support MacOS and refuses to provide a web interface to a Macintosh. If, however, Safari is set to report itself as being Internet Explorer, the card works perfectly; this is obviously an arbitrary exclusion.
The appeal of the digital sender, at least to me, was platform independence. I didn't want to need to fiddle around with unsupported, closed-source drivers under Linux, nor did I want to support a Windows system sitting right next to a scanner simply to support scanning and faxing documents. That said, HP never claimed that the system was capable of working with any OS but Windows.
Configuring the Digital Sender
The JetDirect card in the 8100c can be configured via DHCP, BOOTP, or manual settings. I find it to be easiest to use a statically assigned DHCP address. The settings can be modified at the front panel or through the web interface.
With the exception of the network configuration, the settings on the digital sender need to be entered at the keyboard of the unit. Since the keyboard isn't very good — there's no way to touch-type on it — and the display is marginal, the initial configuration can be a bit tedious. The configuration is saved on the hard drive in the sender, so this should be a one-time process; hopefully any subsequent changes are minor.
The digital sender normally uses the SMTP server on your network to send both email and faxes. Faxes are sent through an electronic fax service; the unit does not contain a modem and cannot send faxes directly. LDAP can be configured to provide email addresses and fax numbers; OpenLDAP works without any issues.
While TCP/IP, SMTP, SNMP and LDAP were easy to configure, faxing took additional research and planning. My goal was to integrate with an existing HylaFAX server on the network.
It turns out that the 8100c sends faxes as simple email messages with the scanned documents attached to the message already encoded as a TIFF file, ready to be transmitted. The destination fax number is the “local part” of the destination email address and the domain is whatever has been configured as the fax service on the digital sender.
To configure faxing through a local fax server, first set the fax provider domain name in the “Settings → I-Fax” menu. I set up a new domain specifically and only for faxing. The most significant benefit to putting faxes on their own domain is ease of control; it is simpler to write rules when all the traffic in a domain should be from an internal network client (or device) to a fax server. Note that the “LAN Fax” functionality is not needed.
My network uses Exim as an MTA; the following recipe will have to be adjusted for other agents. Shown first is the driver section. It will process any mail destination in the “fax.anomalous.net” domain.
fax: driver = accept domains = fax.anomalous.net retry_use_local_part transport = fax_delivery
Next, the driver, which is referenced from
the fax transport. Note that it invokes the
script, which is run as the user “exim.” The mail
message is delivered to
fax_delivery: driver = pipe command = "/usr/bin/fax.pl $local_part" user = exim
Last, fax.pl is a small PERL script that simply breaks out the TIFF data from the email received from the digital sender, decodes the MIME-encoded image and pipes it to “sendfax” with the proper parameters (including the phone number, of course, which is taken from the command line.
If you are considering implementing a system similar to this, you may wish to give further thought to either “hardening” the PERL script or locking down access to the fax mail domain. This is easily done if only a few devices need access to send faxes, and is a worthwhile process even in a small network setting.
Keep In Mind…
- Make an image of the hard drive. The system originally came with a 4GB drive; this is the size of a SDRAM card today. There simply is no excuse for not keeping a backup in case of failure. I used a Rosewill RCW-607 IDE-to-USB adapter to connect the drive from the digital sender to a computer, then used "dd" (a standard UNIX command) to copy the raw data — including the partition table — to another system. I have since performed the same process in reverse to copy the image onto a new Maxtor DiamondMax10 200GB PATA drive that I had lying around; it works well, and the new drive is substantially less noisy than the Quantum drive that came with the unit. Yes, 196GB of the drive is wasted. I intend to test out a SDRAM card with an IDE-to-SDRAM adapter in place of the hard drive. If it works, it will consume less energy and be completely silent.
- The power supply appears to be a low-budget unit. While I haven't experienced any problems with it, I'm concerned for the future. Worse, it's not a standard PC-type power supply, though it obviously does produce standard voltages. My fingers are crossed on this one; hopefully I'll be able to repair or replace it if a problem occurs.
- The “glass” scanning surface is actually plastic and has not aged particularly well; it is starting to get cloudy. I intend to remove the plastic and see if a piece of glass can be mounted in its place.
- The keyboard really is awful, but the keys don't “bounce” and it has been quite serviceable. I wouldn't want to do a lot of typing on it, but then again, you don't need to — it's only for entering email addresses and fax numbers.
- The LCD display doesn't have a backlight. This is a significant inconvenience to me; I keep my office dim. The more-expensive-at-the-time Digital Sender 9100c has a nicer backlit display. I hope to look into a retrofit.
- The software in the digital sender appears to be written using VRTX, a real-time operating system that I know from my work at Motorola, where it was used in cellular infrastructure equipment. VRTX contains extensions to read and write DOS FAT partitions, and you will find that some of the partitions on the hard drive can be mounted. In them, you'll find some interesting test data as well as your configuration, which is retained in two separate locations for greater reliability.
- I haven't had any problems, but there are numerous reports of people who corrupted the hard drive image by shutting down the digital sender without properly “halting” it. To shut it down cleanly, press the “Alt,” “Shift,” and “Stop” buttons simultaneously.