Acces PCI-ICM422/2, User Manual

Page 3-1

Manual MPCI-ICM4S.F1b

Figure 3-1:  

Simplified Termination Schematic

Chapter 3:  Option Selection

To help you locate the jumpers described in this section,  refer to the Option Selection Map at the
end of this chapter.  Operation is determined by jumper installation as described in the following
paragraphs.

Terminations

A transmission line should be terminated at
the receiving end in its characteristic
impedance. Installing a jumper at the
locations labeled  LDO and LDI apply
120

S

 loads  across the transmit (LDO)and

receive (LDI) lines.

In operations where there are multiple terminals, only the ports at each end of the network should
have terminating impedance as described above. Also, for  RS485 operation, there must be a bias
on the RX+ and RX- lines.  If the PCI-ICM485 card is not to provide that bias in your application,
contact the factory.

Baud Rate Ranges

For each of the ports, jumpers labeled X1 and X4 provide means to select baud rates in either of two
ranges.  When in the "X1" position, the baud rate range is up to 115,200 baud.  When in the "X4"
position, the baud rate range is 200 to 460,800 baud.  Refer to the Baud Rate Divisor Table on page
5-2 of the manual.

Interrupts

Please note that, in Windows NT systems, changes must be made to the system registry to support
IRQ sharing.  The following is excerpted from "Controlling Multiport Serial I/O Cards"provided by
Microsoft in the MSDN library, documentid: mk: @ivt: nt40res/ D15/S55FC.HTM, also available
in the WindowsNT Resource Kit. 

The Microsoft serial driver can be used to control many dumb multiport serial cards.  Dumb
indicates that the control includes no on-board processor.  Each port of a multiport card has a
separate subkey under the HKLM\CurrentControlSet\Services\Serial subkey in the registry.  In each
of these subkeys, you must add values for DosDevices, Interrupt, InterruptStatus, PortAddress, and
PortIndex because these are not detected by the Hardware Recognizer. (For descriptions and ranges
for these values, see Regentry.hlp, the Registry help file on the WindowsNT Workstation Resource
Kit CD.)