Compatible Switchboxes for 692C
Brent A. Heidman
Can anyone recommend a switchbox that will work with the HP DeskJet 692C?
I have a Startech AutoSwitch Bidirectional 2 to 1 Parallel switchbox but it
doesn't seem to want to allow for two way communication between the printer
and computer. Anyone using a switchbox with their DeskJet 692C?
Thanks for any help...
Brent
Robert J. Niland
Don't use a switch. I used to use one. It sort-of mostly worked,
but was a nuisance. I no longer use it.
If you have a spare ISA slot, you can get a simple LPT2 parallel card
for $12 or so. I'm using such a card with a DeskJet 855C (a LaserJet
4M+D is connected to the LPT1 ECP/EPP port). For a few dollars more,
you can get an ECP/EPP ISA card.
Not only does an LPT2 card eliminate switch problems, it allows you to
print to both printers simultaneously, which I sometimes do.
If your PC has networking (or a spare PCI slot for a network card),
consider using an external LAN printer adaptor, like the HP "JetDirect
EX" boxes. Be sure your LAN printer is supported in LAN use first, as
for example, many HP DeskJets are not. The 820 in particular just
plain won't work in that configuration.
If you insist on using a switch, use this checklist.
1. Decide to accept some risk. Some printer vendors, such as HP, don't
support the use of their printers with switchboxes, for reasons which
are probably becoming apparent to you. Problems can range from
"unreliable results" to "maximum smoke". If you damage any hardware,
it may not be covered by warranty.
2. Make sure your drivers allow it. Some drivers, and the HP DeskJets
are often like this, do not tolerate other drivers spooling to the
same LPT, even when not used at the same time. Sometimes you can
work around this by [re-]installing the drivers in a particular
order, sometimes not.
Gonna Switch Anyway? Box Selection
3. Get a 36-pin switch, and not a 25-pin switch. Yes, this means that
the cables from the box to the printers must be 36-to-36 pin. Only
the PC-to-box cable will be 25-to-36 pin.
4. Get a fully metal box (all 6 sides), to keep radiated EMI
(electromagnetic interference) in and induced EMI out. Make sure the
electrical connection from connector ground is solid.
5. Get a box with transient suppression on the signal lines. If you
can't find one, see if you can find two pass-through parallel surge
protectors, and connect one to each printer port on the switch box.
6. Get a box on which the ground lines (shields, safety and signal) are
NOT switched, but everything else is.
7. Make sure all the other lines are present. This is a particular
problem when using 25-to-25-pin RS-232C serial switches with parallel
connections, as serial only needs 8 or 9 pins, and the rest are often
not connected. A 36-to-36 box is less likely to have this problem.
8. Get a box that has a Break-Before-Make switch, so that there is no
risk that signal lines between the two printers will ever be
connected to each other. If it is Make-Before-Break, or you aren't
sure, then...
8a. Get a box that has A-B-C positions (if you have two printers),
and connect the printers to positions A and C. You now have
Break-Before-Make.
9. Get a MECHANICAL switch box. Do NOT get an "active", "electronic"
or "auto-sensing printer sharing" switchbox. Switches with active
electronics are unlikely to support the bi-directional I/O, ECP or
EPP modes used by modern printers.
Cables
10. At the very least get shielded cables.
11. Preferrably, get IEEE-1284 compliant cables. These are widely
available in 25-to-36 pin, but may be harder to find in 36-to-36.
12. Keep total cable length short, probably less than 10 feet between PC
and either printer.
Switch Use
13. If possible, never operate the switch while the system is on.
Decide before power-up which printer you need. Since this is often
impractical, then...
14. Always power down both printers before throwing the switch. Then
turn on the one you need.
Regards, 1001-A East Harmony Road
Bob Niland Suite 503
Internet: r...@sni.net Fort Collins
Unless otherwise specifically stated, Colorado 80525 USA
expressing personal opinions and NOT
speaking for any employer, client or
Internet Service Provider.
Brent A. Heidman
>Don't use a switch. I used to use one. It sort-of mostly worked,
>but was a nuisance. I no longer use it.
>
>If you have a spare ISA slot, you can get a simple LPT2 parallel card
>for $12 or so. I'm using such a card with a DeskJet 855C (a LaserJet
>4M+D is connected to the LPT1 ECP/EPP port). For a few dollars more,
>you can get an ECP/EPP ISA card.
>
>Not only does an LPT2 card eliminate switch problems, it allows you to
>print to both printers simultaneously, which I sometimes do.
This is probably what I will end up doing since I do have a spare ISA
slot. What is the added benefit of getting an ECP/EPP ISA card?
Thanks for the rest of that info also. I'll be able to use it at work in
the not so far off future. Thanks again..
Brent