2
SECTION 3.
OPTION SELECTION
The board contains several jumper straps for each port. These jumper straps must be set for
proper operation.
PORT ENABLE / DISABLE
Each port on the MIL-188-C / MIL-188-114 adapter
can be enabled or disabled with switch
position 8 on the dip-switch. The port is enabled with the switch "On" or "Closed" and
disabled when "Off" or "Open". If any port is disabled, be sure to also disable the interrupt
request for that port by removing the IRQ jumper (see Figure 3).
INTERFACE SELECTION:
E1:
Determines whether the receiver interface is MIL-188-C single-ended unbalanced,
or MIL-188-114 balanced differential. With the jumpers at E1 installed, MIL-188-C
is selected, and the inverting receiver input is grounded. With the jumpers
removed, or floating on one pin, the MIL-188-114 differential interface is selected.
NOTE:
You must either install or remove all four jumpers. Any other combination of
jumpers (i.e. one on three off) is not a valid combination and can cause erratic
data.
E2:
These headers select the interrupt request for each serial port. If COM1: is
selected, this jumper must be on the IRQ4 setting. If COM2: is selected, this
jumper must be on IRQ3.
NOTE
:
Most communications software applications default COM3: to IRQ4 and COM4: to
IRQ3. This requires the sharing of interrupts between COM1: and COM3:, and
between COM2: and COM4:. While this is the default, it is not always the preferred
setting. Check your software configuration instructions to determine the
most
appropriate IRQ selection.
FIGURE 3
HEADER E2 ILLUSTRATION (IRQ 4 SELECTED)
Any two or more ports can share a common IRQ by placing the jumpers on the same IRQ
setting and setting the appropriate selections at E4. Consult your particular software for IRQ
selection. If no interrupt is desired, remove the jumper.
NOTE:
IRQ 2 on "AT" class machines is not available . IRQ 9 is substituted in place of
IRQ 2. To select IRQ 9 place jumper on the IRQ 2 position.
