Measurement Computing CIO-DAC08/16 - Manual (Page 9)

This jumper affects ONLY the power-up / reset condition of the DACs. It is here to
insure that when the computer is turned on, or, if the computer is reset, process
controls will come up in a known, safe state.
Figure 3-3. Initial State Range Select Jumper Positions
If your application requires that the output of all DACs maintain a zero state initially,
you should use simultaneous update mode. This mode allows you to set the value
stored in the output registers before the output voltage is updated. If individual update
mode is used, the value of all DAC outputs will be updated to whatever value is stored
in the output registers at the moment that the first DAC is updated. This value is
undefined but typically will be + full scale (register value = FFFFh).
Using the simultaneous mode allows you to set the values of all registers before any of
the DACs are updated to the register value.
3.4 SIMULTANEOUS UPDATE JUMPER
This jumper selects either individual DAC update when the MSB register is written
(UPDATE) or simultaneous transfer of data to all DAC outputs on a read (XFER). In
simultaneous transfer mode, new output data is loaded into the DAC registers, but the
DAC outputs do not change until one of the registers have been read. The
simultaneous update occurs whenever any of the CIO-DAC16/16 addresses BASE + 0
through BASE + 31 (or addresses BASE + 0 through BASE + 15 for the DAC08) are
read (Figure 3-4).
Figure 3-4. Simultaneous Update Jumper
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