Black Box PI750A, Руководство пользователя

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CHAPTER 7: Operation
7.4 Operating Daisychained or Cascaded MPS-VIIIs
If you have installed more than one Multiport Spooler VIII and connected
them together in a daisychain or cascade, there are several special concerns
you must keep in mind.
Firstly, you must make sure that the timeouts are set appropriately for your
output ports. For single-unit installations, output-port timeouts can be set to
one second, because jobs don’t have to be output until they’ve been received
in full. By contrast, in multiple-unit installations the data is passed through
the intermediate MPS-VIIIs immediately; any delay in a job caused by
computer processing must be allowed for, not only by the input port of
the destination MPS-VIII, but by the input and output ports of all units in
between as well. If you have not already done so during configuration, use the
UCTP’s
Modify Time-Out menu command (see Section 7.3.2 ) or /T direct
command (see the entry for that command in Appendix D ) to set the
timeouts of the output ports connected to other MPS-VIIIs to longer than
the timeouts of the corresponding input ports on the connected MPS-VIIIs.
Secondly, to make sure that your commands (including timeout-setting
commands) go to the right MPS-VIII and that your jobs go to the right
peripherals, you must manipulate the token very carefully (see
Section 7.3.3
).
For example, perhaps you have three MPS-VIIIs connected in a daisychain
(one unit sending output to a second, which in turn sends output to a third),
and you want to send a print job to a printer connected to Port 4 of the third
unit. If the token were already set to 2 and the proper output ports on the first
and second MPS-VIIIs were selected, commands and data would pass through
the first and second units and be processed by the third; you would simply
select Port 4 and send your job, and it would go to the right place. However,
let’s suppose the token is set to 0; commands will go to the first MPS-VIII and
no farther. The first thing to do is select the output port on the first MPS-VIII
that is connected to the second unit. Having done that, set the token to 1 (so
that the first unit will pass the command through) and select the output port
on the second MPS-VIII that is connected to the third unit. Now set the token
to 2, so that subsequent commands will be passed through to the third unit,
and select Port 4. At last you can send your print job to the desired printer.
(When you send direct commands, you can skip the token-setting steps,
because you can include the token, set to your desired number, in the
command itself. See
Section D.2.3 in Appendix D .)