4.1.2
Start of Conversion Register
The start of conversion register is 16-bit write only and performs two functions:
1. When configured for internal triggering, writing a "0" to this register generates the
software trigger, starting the data conversion process.
2. Writing a "0" to this register at any time resets the VALID bit in the control word
register. This allows the VALID bit to be reset at any time during the conversion
process or before the event of an external trigger.
4.1.3
DAC0 Register
An output to this register causes the lower twelve bits of data to be converted to an analog
output on D/A converter channel 0. The four most significant bits of data are ignored. This
register is 16-bit write only.
4.1.4
DAC1 Register
An output to this register causes the lower twelve bits of data to be converted to an analog
output on D/A converter channel 1. The four most significant bits of data are ignored. This
register is 16-bit write only.
The remaining four registers are contained in an 8254 counter/timer.
4.1.5
Clock Rate Register (low word)
The low word of the clock divider is contained in counter 0 of an 8254 counter/timer. The
output of this counter is cascaded into the input of counter 1 to produce a 32-bit timer. Mode
2 must be selected for counter 0 with a minimum count of 2. This register is 8-bit read/write.
4.1.6
Clock Rate Register (high word)
The high word of the clock divider is contained in counter 1 of the 8254 counter/timer. Mode
2 must be selected for counter 1 with a minimum count of 2. This register is 8-bit read/write.
4.1.7
Multi-Function Timer Register
The multi-function timer is implemented using counter 2 of the 8254 counter/timer. Mode
2 must be selected for this timer with a minimum count of 2. This register is 8-bit read/write.
4.1.8
8254 Control Word/Status Register
This register is used to program the mode and report the status of the 8254 counter/timer.
This register is 8-bit read/write.
DAQ-16 Users Manual 27
