Measurement-computing COM232/8AT Instrukcja Użytkownika Pobierz pdf (Strona 4)

4 COM232/8AT User’s Guide March 1998 1000-0901, rev 1.1

Addressing

The COM232/8AT uses eight I/O address locations per port. Full 16-bit address decoding allows base

address selections in the range: 0000 to FFFF Hex. Two DIP switches, designated SW1 and SW2, are

used to specify the adapter’s base address as follows:

• SW1 determines the address setting for A15 through A10.

• SW2 determines the address setting for A9 through A6.

The adapter uses the remaining address inputs to determine the channel and register being used.

The address of each port is incremented by a factor of

8 (in hexadecimal code) from the base address. For

this reason, 64 address locations are used, as indicated

by the table at the right. Note that SW1, SW2, and

other component locations can be referenced on the

figure, COM232/8AT Layout Reference, on page 6.

The following three figures serve as sample switch settings. Note that there are 6 “hidden” settings,

each with a fixed value of zero. These hidden settings have been included in the following illustrations.

64 Address Locations

Port Range Port Range

thru

7 5 32

thru

15 6 40

thru

316

thru

23 7 48

thru

424

thru

31 8 56

thru

1 2 3 4 5 6 7 8 9 ... 19 20

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Measurement-computing COM232/8AT Instrukcja Użytkownika Strona 4