User manual

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.
120
0.1 F
Tx+/Rx
+
Tx-/Rx-
COM422LD
:
Figure 3-1: Simplified Termination Schematic
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 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.)
For example, if you have a four-port card configured to use address 0xFC00, 0xFD00, 0xFD80, and
0xFE00 with an interrupt of 05, the values in the Registry are:
Manual PCI-ICM-422(485)/2(4)
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