M-AUDIO Biport 2x4s - Manual (Page 21)

• The loopback MIDI cable is incorrectly connected. Check to make
sure that you have a MIDI cable connected between the BiPort MIDI
In and the BiPort MIDI Out selected in the diagnostic program. There
should be no MIDI instruments, mergers, or thru boxes connected to
the BiPort during this test; it is a closed-loop test with one MIDI cable
connected between two MIDI jacks of the BiPort.
• The MIDI cable you are using to loopback data is defective.
• The BiPort is defective. This is extremely rare as the BiPort units are
tested rigorously at the factory before shipping. If you think this is
the case, please contact MIDIMAN Technical Support.
4. Receive Interrupt Test
This test verifies the reception of data from the BiPort under interrupt
(IRQ) control. If this test fails, it is host serial port related. More specifi-
cally it is almost always host IRQ-related.
Most computers use IRQ4 for COM1 and IRQ3 for COM2. If you have
the BiPort connected to COM1 on your computer and have IRQ=4 set in
BI24DIAG.EXE, but it fails the Receive Interrupt Test, you could have an
internal modem connected COM1 or another odd numbered COM port
using the same IRQ. Another possibility is a driver associated with
another device used on the same serial port is adversely affecting the
IRQ. Yet one more possibility is that your serial port IRQ is disabled in
your computer’s BIOS CMOS setup, and simply needs to be switched
on.
If you are unsure what your port IRQ is or how to find out, please see
the section in this manual titled “Selecting a Host Serial Port,” or consult
your computer owner’s manual or computer manufacturer directly.
5. SMPTE I/O Test
This test makes sure that the SMPTE In and Out jacks are functioning
properly. If this test fails, make sure that the cable you have looped from
SMPTE In to SMPTE Out is good, and also properly connected.
PC Drivers and Driver Installation
MIDI application software communicates with the BiPort 2x4s via soft-
ware “drivers.” Basically, a Windows software driver is a special dedi-
cated program that makes a MIDI interface accessible to any Windows
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