User`s guide

Registers • 23
3.4 A/D Channel Control Register
The PCI-9111 provides 16 single-ended analog input channels. The channel
control register is used to set the A/D channels to be converted. Under
non-auto scanning mode, the register sets the channel number for conversion.
Under auto-scanning mode, the register sets the ending channel number.
Address: BASE + 6h
Attribute: write only
Data Format:
Bit 7 6 5 4 3 2 1 0
BASE+6h CN7 CN6 CN5 CN4 CN3 CN2 CN1 CN0
BASE+7h -- -- -- -- -- -- -- --
Where:
CNn: channel number. (CN7 is MSB and CN0 is LSB).
There are 8 bits in this register. The 4 LSB (CN0~CN3) are used to select the
on-board multiplexer. Usually, only the 4 LSB are used and 16 input channels
can be selected. However, if there is an extension board, which can provide
extension ability to 256 analog input channels, the 4 MSB (CN4~CN7) can also
be used to control the extension board.
3.5 A/D Channel Read Back Register
The AD channel setting can be read back from this register.
Address: BASE + 6h
Attribute: read only
Data Format:
Bit 7 6 5 4 3 2 1 0
BASE+6h AS3 AS2 AS1 AS0 CN3 CN2 CN1 CN0
BASE+7h -- -- -- -- -- -- -- --
Where:
CNn: channel number
ASn: Auto scan channel number.